jaroslav@597: /*
jaroslav@597: * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
jaroslav@597: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@597: *
jaroslav@597: * This code is free software; you can redistribute it and/or modify it
jaroslav@597: * under the terms of the GNU General Public License version 2 only, as
jaroslav@597: * published by the Free Software Foundation. Oracle designates this
jaroslav@597: * particular file as subject to the "Classpath" exception as provided
jaroslav@597: * by Oracle in the LICENSE file that accompanied this code.
jaroslav@597: *
jaroslav@597: * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@597: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@597: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
jaroslav@597: * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@597: * accompanied this code).
jaroslav@597: *
jaroslav@597: * You should have received a copy of the GNU General Public License version
jaroslav@597: * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@597: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@597: *
jaroslav@597: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@597: * or visit www.oracle.com if you need additional information or have any
jaroslav@597: * questions.
jaroslav@597: */
jaroslav@597:
jaroslav@597: package java.util;
jaroslav@597: import java.io.Serializable;
jaroslav@597: import java.io.IOException;
jaroslav@597: import java.lang.reflect.Array;
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * This class consists exclusively of static methods that operate on or return
jaroslav@597: * collections. It contains polymorphic algorithms that operate on
jaroslav@597: * collections, "wrappers", which return a new collection backed by a
jaroslav@597: * specified collection, and a few other odds and ends.
jaroslav@597: *
jaroslav@597: * The methods of this class all throw a NullPointerException
jaroslav@597: * if the collections or class objects provided to them are null.
jaroslav@597: *
jaroslav@597: *
The documentation for the polymorphic algorithms contained in this class
jaroslav@597: * generally includes a brief description of the implementation. Such
jaroslav@597: * descriptions should be regarded as implementation notes, rather than
jaroslav@597: * parts of the specification. Implementors should feel free to
jaroslav@597: * substitute other algorithms, so long as the specification itself is adhered
jaroslav@597: * to. (For example, the algorithm used by sort does not have to be
jaroslav@597: * a mergesort, but it does have to be stable.)
jaroslav@597: *
jaroslav@597: *
The "destructive" algorithms contained in this class, that is, the
jaroslav@597: * algorithms that modify the collection on which they operate, are specified
jaroslav@597: * to throw UnsupportedOperationException if the collection does not
jaroslav@597: * support the appropriate mutation primitive(s), such as the set
jaroslav@597: * method. These algorithms may, but are not required to, throw this
jaroslav@597: * exception if an invocation would have no effect on the collection. For
jaroslav@597: * example, invoking the sort method on an unmodifiable list that is
jaroslav@597: * already sorted may or may not throw UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: *
This class is a member of the
jaroslav@597: *
jaroslav@597: * Java Collections Framework.
jaroslav@597: *
jaroslav@597: * @author Josh Bloch
jaroslav@597: * @author Neal Gafter
jaroslav@597: * @see Collection
jaroslav@597: * @see Set
jaroslav@597: * @see List
jaroslav@597: * @see Map
jaroslav@597: * @since 1.2
jaroslav@597: */
jaroslav@597:
jaroslav@597: public class Collections {
jaroslav@597: // Suppresses default constructor, ensuring non-instantiability.
jaroslav@597: private Collections() {
jaroslav@597: }
jaroslav@597:
jaroslav@597: // Algorithms
jaroslav@597:
jaroslav@597: /*
jaroslav@597: * Tuning parameters for algorithms - Many of the List algorithms have
jaroslav@597: * two implementations, one of which is appropriate for RandomAccess
jaroslav@597: * lists, the other for "sequential." Often, the random access variant
jaroslav@597: * yields better performance on small sequential access lists. The
jaroslav@597: * tuning parameters below determine the cutoff point for what constitutes
jaroslav@597: * a "small" sequential access list for each algorithm. The values below
jaroslav@597: * were empirically determined to work well for LinkedList. Hopefully
jaroslav@597: * they should be reasonable for other sequential access List
jaroslav@597: * implementations. Those doing performance work on this code would
jaroslav@597: * do well to validate the values of these parameters from time to time.
jaroslav@597: * (The first word of each tuning parameter name is the algorithm to which
jaroslav@597: * it applies.)
jaroslav@597: */
jaroslav@597: private static final int BINARYSEARCH_THRESHOLD = 5000;
jaroslav@597: private static final int REVERSE_THRESHOLD = 18;
jaroslav@597: private static final int SHUFFLE_THRESHOLD = 5;
jaroslav@597: private static final int FILL_THRESHOLD = 25;
jaroslav@597: private static final int ROTATE_THRESHOLD = 100;
jaroslav@597: private static final int COPY_THRESHOLD = 10;
jaroslav@597: private static final int REPLACEALL_THRESHOLD = 11;
jaroslav@597: private static final int INDEXOFSUBLIST_THRESHOLD = 35;
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Sorts the specified list into ascending order, according to the
jaroslav@597: * {@linkplain Comparable natural ordering} of its elements.
jaroslav@597: * All elements in the list must implement the {@link Comparable}
jaroslav@597: * interface. Furthermore, all elements in the list must be
jaroslav@597: * mutually comparable (that is, {@code e1.compareTo(e2)}
jaroslav@597: * must not throw a {@code ClassCastException} for any elements
jaroslav@597: * {@code e1} and {@code e2} in the list).
jaroslav@597: *
jaroslav@597: *
This sort is guaranteed to be stable: equal elements will
jaroslav@597: * not be reordered as a result of the sort.
jaroslav@597: *
jaroslav@597: *
The specified list must be modifiable, but need not be resizable.
jaroslav@597: *
jaroslav@597: *
Implementation note: This implementation is a stable, adaptive,
jaroslav@597: * iterative mergesort that requires far fewer than n lg(n) comparisons
jaroslav@597: * when the input array is partially sorted, while offering the
jaroslav@597: * performance of a traditional mergesort when the input array is
jaroslav@597: * randomly ordered. If the input array is nearly sorted, the
jaroslav@597: * implementation requires approximately n comparisons. Temporary
jaroslav@597: * storage requirements vary from a small constant for nearly sorted
jaroslav@597: * input arrays to n/2 object references for randomly ordered input
jaroslav@597: * arrays.
jaroslav@597: *
jaroslav@597: *
The implementation takes equal advantage of ascending and
jaroslav@597: * descending order in its input array, and can take advantage of
jaroslav@597: * ascending and descending order in different parts of the same
jaroslav@597: * input array. It is well-suited to merging two or more sorted arrays:
jaroslav@597: * simply concatenate the arrays and sort the resulting array.
jaroslav@597: *
jaroslav@597: *
The implementation was adapted from Tim Peters's list sort for Python
jaroslav@597: * (
jaroslav@597: * TimSort). It uses techiques from Peter McIlroy's "Optimistic
jaroslav@597: * Sorting and Information Theoretic Complexity", in Proceedings of the
jaroslav@597: * Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
jaroslav@597: * January 1993.
jaroslav@597: *
jaroslav@597: *
This implementation dumps the specified list into an array, sorts
jaroslav@597: * the array, and iterates over the list resetting each element
jaroslav@597: * from the corresponding position in the array. This avoids the
jaroslav@597: * n2 log(n) performance that would result from attempting
jaroslav@597: * to sort a linked list in place.
jaroslav@597: *
jaroslav@597: * @param list the list to be sorted.
jaroslav@597: * @throws ClassCastException if the list contains elements that are not
jaroslav@597: * mutually comparable (for example, strings and integers).
jaroslav@597: * @throws UnsupportedOperationException if the specified list's
jaroslav@597: * list-iterator does not support the {@code set} operation.
jaroslav@597: * @throws IllegalArgumentException (optional) if the implementation
jaroslav@597: * detects that the natural ordering of the list elements is
jaroslav@597: * found to violate the {@link Comparable} contract
jaroslav@597: */
jaroslav@597: public static > void sort(List list) {
jaroslav@597: Object[] a = list.toArray();
jaroslav@597: Arrays.sort(a);
jaroslav@597: ListIterator i = list.listIterator();
jaroslav@597: for (int j=0; jmutually
jaroslav@597: * comparable using the specified comparator (that is,
jaroslav@597: * {@code c.compare(e1, e2)} must not throw a {@code ClassCastException}
jaroslav@597: * for any elements {@code e1} and {@code e2} in the list).
jaroslav@597: *
jaroslav@597: * This sort is guaranteed to be stable: equal elements will
jaroslav@597: * not be reordered as a result of the sort.
jaroslav@597: *
jaroslav@597: *
The specified list must be modifiable, but need not be resizable.
jaroslav@597: *
jaroslav@597: *
Implementation note: This implementation is a stable, adaptive,
jaroslav@597: * iterative mergesort that requires far fewer than n lg(n) comparisons
jaroslav@597: * when the input array is partially sorted, while offering the
jaroslav@597: * performance of a traditional mergesort when the input array is
jaroslav@597: * randomly ordered. If the input array is nearly sorted, the
jaroslav@597: * implementation requires approximately n comparisons. Temporary
jaroslav@597: * storage requirements vary from a small constant for nearly sorted
jaroslav@597: * input arrays to n/2 object references for randomly ordered input
jaroslav@597: * arrays.
jaroslav@597: *
jaroslav@597: *
The implementation takes equal advantage of ascending and
jaroslav@597: * descending order in its input array, and can take advantage of
jaroslav@597: * ascending and descending order in different parts of the same
jaroslav@597: * input array. It is well-suited to merging two or more sorted arrays:
jaroslav@597: * simply concatenate the arrays and sort the resulting array.
jaroslav@597: *
jaroslav@597: *
The implementation was adapted from Tim Peters's list sort for Python
jaroslav@597: * (
jaroslav@597: * TimSort). It uses techiques from Peter McIlroy's "Optimistic
jaroslav@597: * Sorting and Information Theoretic Complexity", in Proceedings of the
jaroslav@597: * Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
jaroslav@597: * January 1993.
jaroslav@597: *
jaroslav@597: *
This implementation dumps the specified list into an array, sorts
jaroslav@597: * the array, and iterates over the list resetting each element
jaroslav@597: * from the corresponding position in the array. This avoids the
jaroslav@597: * n2 log(n) performance that would result from attempting
jaroslav@597: * to sort a linked list in place.
jaroslav@597: *
jaroslav@597: * @param list the list to be sorted.
jaroslav@597: * @param c the comparator to determine the order of the list. A
jaroslav@597: * {@code null} value indicates that the elements' natural
jaroslav@597: * ordering should be used.
jaroslav@597: * @throws ClassCastException if the list contains elements that are not
jaroslav@597: * mutually comparable using the specified comparator.
jaroslav@597: * @throws UnsupportedOperationException if the specified list's
jaroslav@597: * list-iterator does not support the {@code set} operation.
jaroslav@597: * @throws IllegalArgumentException (optional) if the comparator is
jaroslav@597: * found to violate the {@link Comparator} contract
jaroslav@597: */
jaroslav@597: public static void sort(List list, Comparator c) {
jaroslav@597: Object[] a = list.toArray();
jaroslav@597: Arrays.sort(a, (Comparator)c);
jaroslav@597: ListIterator i = list.listIterator();
jaroslav@597: for (int j=0; jThis method runs in log(n) time for a "random access" list (which
jaroslav@597: * provides near-constant-time positional access). If the specified list
jaroslav@597: * does not implement the {@link RandomAccess} interface and is large,
jaroslav@597: * this method will do an iterator-based binary search that performs
jaroslav@597: * O(n) link traversals and O(log n) element comparisons.
jaroslav@597: *
jaroslav@597: * @param list the list to be searched.
jaroslav@597: * @param key the key to be searched for.
jaroslav@597: * @return the index of the search key, if it is contained in the list;
jaroslav@597: * otherwise, (-(insertion point) - 1). The
jaroslav@597: * insertion point is defined as the point at which the
jaroslav@597: * key would be inserted into the list: the index of the first
jaroslav@597: * element greater than the key, or list.size() if all
jaroslav@597: * elements in the list are less than the specified key. Note
jaroslav@597: * that this guarantees that the return value will be >= 0 if
jaroslav@597: * and only if the key is found.
jaroslav@597: * @throws ClassCastException if the list contains elements that are not
jaroslav@597: * mutually comparable (for example, strings and
jaroslav@597: * integers), or the search key is not mutually comparable
jaroslav@597: * with the elements of the list.
jaroslav@597: */
jaroslav@597: public static
jaroslav@597: int binarySearch(List> list, T key) {
jaroslav@597: if (list instanceof RandomAccess || list.size()
jaroslav@597: int indexedBinarySearch(List> list, T key)
jaroslav@597: {
jaroslav@597: int low = 0;
jaroslav@597: int high = list.size()-1;
jaroslav@597:
jaroslav@597: while (low <= high) {
jaroslav@597: int mid = (low + high) >>> 1;
jaroslav@597: Comparable midVal = list.get(mid);
jaroslav@597: int cmp = midVal.compareTo(key);
jaroslav@597:
jaroslav@597: if (cmp < 0)
jaroslav@597: low = mid + 1;
jaroslav@597: else if (cmp > 0)
jaroslav@597: high = mid - 1;
jaroslav@597: else
jaroslav@597: return mid; // key found
jaroslav@597: }
jaroslav@597: return -(low + 1); // key not found
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static
jaroslav@597: int iteratorBinarySearch(List> list, T key)
jaroslav@597: {
jaroslav@597: int low = 0;
jaroslav@597: int high = list.size()-1;
jaroslav@597: ListIterator> i = list.listIterator();
jaroslav@597:
jaroslav@597: while (low <= high) {
jaroslav@597: int mid = (low + high) >>> 1;
jaroslav@597: Comparable midVal = get(i, mid);
jaroslav@597: int cmp = midVal.compareTo(key);
jaroslav@597:
jaroslav@597: if (cmp < 0)
jaroslav@597: low = mid + 1;
jaroslav@597: else if (cmp > 0)
jaroslav@597: high = mid - 1;
jaroslav@597: else
jaroslav@597: return mid; // key found
jaroslav@597: }
jaroslav@597: return -(low + 1); // key not found
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Gets the ith element from the given list by repositioning the specified
jaroslav@597: * list listIterator.
jaroslav@597: */
jaroslav@597: private static T get(ListIterator i, int index) {
jaroslav@597: T obj = null;
jaroslav@597: int pos = i.nextIndex();
jaroslav@597: if (pos <= index) {
jaroslav@597: do {
jaroslav@597: obj = i.next();
jaroslav@597: } while (pos++ < index);
jaroslav@597: } else {
jaroslav@597: do {
jaroslav@597: obj = i.previous();
jaroslav@597: } while (--pos > index);
jaroslav@597: }
jaroslav@597: return obj;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Searches the specified list for the specified object using the binary
jaroslav@597: * search algorithm. The list must be sorted into ascending order
jaroslav@597: * according to the specified comparator (as by the
jaroslav@597: * {@link #sort(List, Comparator) sort(List, Comparator)}
jaroslav@597: * method), prior to making this call. If it is
jaroslav@597: * not sorted, the results are undefined. If the list contains multiple
jaroslav@597: * elements equal to the specified object, there is no guarantee which one
jaroslav@597: * will be found.
jaroslav@597: *
jaroslav@597: * This method runs in log(n) time for a "random access" list (which
jaroslav@597: * provides near-constant-time positional access). If the specified list
jaroslav@597: * does not implement the {@link RandomAccess} interface and is large,
jaroslav@597: * this method will do an iterator-based binary search that performs
jaroslav@597: * O(n) link traversals and O(log n) element comparisons.
jaroslav@597: *
jaroslav@597: * @param list the list to be searched.
jaroslav@597: * @param key the key to be searched for.
jaroslav@597: * @param c the comparator by which the list is ordered.
jaroslav@597: * A null value indicates that the elements'
jaroslav@597: * {@linkplain Comparable natural ordering} should be used.
jaroslav@597: * @return the index of the search key, if it is contained in the list;
jaroslav@597: * otherwise, (-(insertion point) - 1). The
jaroslav@597: * insertion point is defined as the point at which the
jaroslav@597: * key would be inserted into the list: the index of the first
jaroslav@597: * element greater than the key, or list.size() if all
jaroslav@597: * elements in the list are less than the specified key. Note
jaroslav@597: * that this guarantees that the return value will be >= 0 if
jaroslav@597: * and only if the key is found.
jaroslav@597: * @throws ClassCastException if the list contains elements that are not
jaroslav@597: * mutually comparable using the specified comparator,
jaroslav@597: * or the search key is not mutually comparable with the
jaroslav@597: * elements of the list using this comparator.
jaroslav@597: */
jaroslav@597: public static int binarySearch(List list, T key, Comparator c) {
jaroslav@597: if (c==null)
jaroslav@597: return binarySearch((List) list, key);
jaroslav@597:
jaroslav@597: if (list instanceof RandomAccess || list.size() int indexedBinarySearch(List l, T key, Comparator c) {
jaroslav@597: int low = 0;
jaroslav@597: int high = l.size()-1;
jaroslav@597:
jaroslav@597: while (low <= high) {
jaroslav@597: int mid = (low + high) >>> 1;
jaroslav@597: T midVal = l.get(mid);
jaroslav@597: int cmp = c.compare(midVal, key);
jaroslav@597:
jaroslav@597: if (cmp < 0)
jaroslav@597: low = mid + 1;
jaroslav@597: else if (cmp > 0)
jaroslav@597: high = mid - 1;
jaroslav@597: else
jaroslav@597: return mid; // key found
jaroslav@597: }
jaroslav@597: return -(low + 1); // key not found
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static int iteratorBinarySearch(List l, T key, Comparator c) {
jaroslav@597: int low = 0;
jaroslav@597: int high = l.size()-1;
jaroslav@597: ListIterator i = l.listIterator();
jaroslav@597:
jaroslav@597: while (low <= high) {
jaroslav@597: int mid = (low + high) >>> 1;
jaroslav@597: T midVal = get(i, mid);
jaroslav@597: int cmp = c.compare(midVal, key);
jaroslav@597:
jaroslav@597: if (cmp < 0)
jaroslav@597: low = mid + 1;
jaroslav@597: else if (cmp > 0)
jaroslav@597: high = mid - 1;
jaroslav@597: else
jaroslav@597: return mid; // key found
jaroslav@597: }
jaroslav@597: return -(low + 1); // key not found
jaroslav@597: }
jaroslav@597:
jaroslav@597: private interface SelfComparable extends Comparable {}
jaroslav@597:
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Reverses the order of the elements in the specified list.
jaroslav@597: *
jaroslav@597: * This method runs in linear time.
jaroslav@597: *
jaroslav@597: * @param list the list whose elements are to be reversed.
jaroslav@597: * @throws UnsupportedOperationException if the specified list or
jaroslav@597: * its list-iterator does not support the set operation.
jaroslav@597: */
jaroslav@597: public static void reverse(List list) {
jaroslav@597: int size = list.size();
jaroslav@597: if (size < REVERSE_THRESHOLD || list instanceof RandomAccess) {
jaroslav@597: for (int i=0, mid=size>>1, j=size-1; i>1; i
jaroslav@597: *
jaroslav@597: * The hedge "approximately" is used in the foregoing description because
jaroslav@597: * default source of randomness is only approximately an unbiased source
jaroslav@597: * of independently chosen bits. If it were a perfect source of randomly
jaroslav@597: * chosen bits, then the algorithm would choose permutations with perfect
jaroslav@597: * uniformity.
jaroslav@597: *
jaroslav@597: * This implementation traverses the list backwards, from the last element
jaroslav@597: * up to the second, repeatedly swapping a randomly selected element into
jaroslav@597: * the "current position". Elements are randomly selected from the
jaroslav@597: * portion of the list that runs from the first element to the current
jaroslav@597: * position, inclusive.
jaroslav@597: *
jaroslav@597: * This method runs in linear time. If the specified list does not
jaroslav@597: * implement the {@link RandomAccess} interface and is large, this
jaroslav@597: * implementation dumps the specified list into an array before shuffling
jaroslav@597: * it, and dumps the shuffled array back into the list. This avoids the
jaroslav@597: * quadratic behavior that would result from shuffling a "sequential
jaroslav@597: * access" list in place.
jaroslav@597: *
jaroslav@597: * @param list the list to be shuffled.
jaroslav@597: * @throws UnsupportedOperationException if the specified list or
jaroslav@597: * its list-iterator does not support the set operation.
jaroslav@597: */
jaroslav@597: public static void shuffle(List list) {
jaroslav@597: Random rnd = r;
jaroslav@597: if (rnd == null)
jaroslav@597: r = rnd = new Random();
jaroslav@597: shuffle(list, rnd);
jaroslav@597: }
jaroslav@597: private static Random r;
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Randomly permute the specified list using the specified source of
jaroslav@597: * randomness. All permutations occur with equal likelihood
jaroslav@597: * assuming that the source of randomness is fair.
jaroslav@597: *
jaroslav@597: * This implementation traverses the list backwards, from the last element
jaroslav@597: * up to the second, repeatedly swapping a randomly selected element into
jaroslav@597: * the "current position". Elements are randomly selected from the
jaroslav@597: * portion of the list that runs from the first element to the current
jaroslav@597: * position, inclusive.
jaroslav@597: *
jaroslav@597: * This method runs in linear time. If the specified list does not
jaroslav@597: * implement the {@link RandomAccess} interface and is large, this
jaroslav@597: * implementation dumps the specified list into an array before shuffling
jaroslav@597: * it, and dumps the shuffled array back into the list. This avoids the
jaroslav@597: * quadratic behavior that would result from shuffling a "sequential
jaroslav@597: * access" list in place.
jaroslav@597: *
jaroslav@597: * @param list the list to be shuffled.
jaroslav@597: * @param rnd the source of randomness to use to shuffle the list.
jaroslav@597: * @throws UnsupportedOperationException if the specified list or its
jaroslav@597: * list-iterator does not support the set operation.
jaroslav@597: */
jaroslav@597: public static void shuffle(List list, Random rnd) {
jaroslav@597: int size = list.size();
jaroslav@597: if (size < SHUFFLE_THRESHOLD || list instanceof RandomAccess) {
jaroslav@597: for (int i=size; i>1; i--)
jaroslav@597: swap(list, i-1, rnd.nextInt(i));
jaroslav@597: } else {
jaroslav@597: Object arr[] = list.toArray();
jaroslav@597:
jaroslav@597: // Shuffle array
jaroslav@597: for (int i=size; i>1; i--)
jaroslav@597: swap(arr, i-1, rnd.nextInt(i));
jaroslav@597:
jaroslav@597: // Dump array back into list
jaroslav@597: ListIterator it = list.listIterator();
jaroslav@597: for (int i=0; ii or j
jaroslav@597: * is out of range (i < 0 || i >= list.size()
jaroslav@597: * || j < 0 || j >= list.size()).
jaroslav@597: * @since 1.4
jaroslav@597: */
jaroslav@597: public static void swap(List list, int i, int j) {
jaroslav@597: final List l = list;
jaroslav@597: l.set(i, l.set(j, l.get(i)));
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Swaps the two specified elements in the specified array.
jaroslav@597: */
jaroslav@597: private static void swap(Object[] arr, int i, int j) {
jaroslav@597: Object tmp = arr[i];
jaroslav@597: arr[i] = arr[j];
jaroslav@597: arr[j] = tmp;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Replaces all of the elements of the specified list with the specified
jaroslav@597: * element.
jaroslav@597: *
jaroslav@597: * This method runs in linear time.
jaroslav@597: *
jaroslav@597: * @param list the list to be filled with the specified element.
jaroslav@597: * @param obj The element with which to fill the specified list.
jaroslav@597: * @throws UnsupportedOperationException if the specified list or its
jaroslav@597: * list-iterator does not support the set operation.
jaroslav@597: */
jaroslav@597: public static void fill(List list, T obj) {
jaroslav@597: int size = list.size();
jaroslav@597:
jaroslav@597: if (size < FILL_THRESHOLD || list instanceof RandomAccess) {
jaroslav@597: for (int i=0; i itr = list.listIterator();
jaroslav@597: for (int i=0; i
jaroslav@597: *
jaroslav@597: * This method runs in linear time.
jaroslav@597: *
jaroslav@597: * @param dest The destination list.
jaroslav@597: * @param src The source list.
jaroslav@597: * @throws IndexOutOfBoundsException if the destination list is too small
jaroslav@597: * to contain the entire source List.
jaroslav@597: * @throws UnsupportedOperationException if the destination list's
jaroslav@597: * list-iterator does not support the set operation.
jaroslav@597: */
jaroslav@597: public static void copy(List dest, List src) {
jaroslav@597: int srcSize = src.size();
jaroslav@597: if (srcSize > dest.size())
jaroslav@597: throw new IndexOutOfBoundsException("Source does not fit in dest");
jaroslav@597:
jaroslav@597: if (srcSize < COPY_THRESHOLD ||
jaroslav@597: (src instanceof RandomAccess && dest instanceof RandomAccess)) {
jaroslav@597: for (int i=0; i di=dest.listIterator();
jaroslav@597: ListIterator si=src.listIterator();
jaroslav@597: for (int i=0; inatural ordering of its elements. All elements in the
jaroslav@597: * collection must implement the Comparable interface.
jaroslav@597: * Furthermore, all elements in the collection must be mutually
jaroslav@597: * comparable (that is, e1.compareTo(e2) must not throw a
jaroslav@597: * ClassCastException for any elements e1 and
jaroslav@597: * e2 in the collection).
jaroslav@597: *
jaroslav@597: * This method iterates over the entire collection, hence it requires
jaroslav@597: * time proportional to the size of the collection.
jaroslav@597: *
jaroslav@597: * @param coll the collection whose minimum element is to be determined.
jaroslav@597: * @return the minimum element of the given collection, according
jaroslav@597: * to the natural ordering of its elements.
jaroslav@597: * @throws ClassCastException if the collection contains elements that are
jaroslav@597: * not mutually comparable (for example, strings and
jaroslav@597: * integers).
jaroslav@597: * @throws NoSuchElementException if the collection is empty.
jaroslav@597: * @see Comparable
jaroslav@597: */
jaroslav@597: public static > T min(Collection coll) {
jaroslav@597: Iterator i = coll.iterator();
jaroslav@597: T candidate = i.next();
jaroslav@597:
jaroslav@597: while (i.hasNext()) {
jaroslav@597: T next = i.next();
jaroslav@597: if (next.compareTo(candidate) < 0)
jaroslav@597: candidate = next;
jaroslav@597: }
jaroslav@597: return candidate;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns the minimum element of the given collection, according to the
jaroslav@597: * order induced by the specified comparator. All elements in the
jaroslav@597: * collection must be mutually comparable by the specified
jaroslav@597: * comparator (that is, comp.compare(e1, e2) must not throw a
jaroslav@597: * ClassCastException for any elements e1 and
jaroslav@597: * e2 in the collection).
jaroslav@597: *
jaroslav@597: * This method iterates over the entire collection, hence it requires
jaroslav@597: * time proportional to the size of the collection.
jaroslav@597: *
jaroslav@597: * @param coll the collection whose minimum element is to be determined.
jaroslav@597: * @param comp the comparator with which to determine the minimum element.
jaroslav@597: * A null value indicates that the elements' natural
jaroslav@597: * ordering should be used.
jaroslav@597: * @return the minimum element of the given collection, according
jaroslav@597: * to the specified comparator.
jaroslav@597: * @throws ClassCastException if the collection contains elements that are
jaroslav@597: * not mutually comparable using the specified comparator.
jaroslav@597: * @throws NoSuchElementException if the collection is empty.
jaroslav@597: * @see Comparable
jaroslav@597: */
jaroslav@597: public static T min(Collection coll, Comparator comp) {
jaroslav@597: if (comp==null)
jaroslav@597: return (T)min((Collection) (Collection) coll);
jaroslav@597:
jaroslav@597: Iterator i = coll.iterator();
jaroslav@597: T candidate = i.next();
jaroslav@597:
jaroslav@597: while (i.hasNext()) {
jaroslav@597: T next = i.next();
jaroslav@597: if (comp.compare(next, candidate) < 0)
jaroslav@597: candidate = next;
jaroslav@597: }
jaroslav@597: return candidate;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns the maximum element of the given collection, according to the
jaroslav@597: * natural ordering of its elements. All elements in the
jaroslav@597: * collection must implement the Comparable interface.
jaroslav@597: * Furthermore, all elements in the collection must be mutually
jaroslav@597: * comparable (that is, e1.compareTo(e2) must not throw a
jaroslav@597: * ClassCastException for any elements e1 and
jaroslav@597: * e2 in the collection).
jaroslav@597: *
jaroslav@597: * This method iterates over the entire collection, hence it requires
jaroslav@597: * time proportional to the size of the collection.
jaroslav@597: *
jaroslav@597: * @param coll the collection whose maximum element is to be determined.
jaroslav@597: * @return the maximum element of the given collection, according
jaroslav@597: * to the natural ordering of its elements.
jaroslav@597: * @throws ClassCastException if the collection contains elements that are
jaroslav@597: * not mutually comparable (for example, strings and
jaroslav@597: * integers).
jaroslav@597: * @throws NoSuchElementException if the collection is empty.
jaroslav@597: * @see Comparable
jaroslav@597: */
jaroslav@597: public static > T max(Collection coll) {
jaroslav@597: Iterator i = coll.iterator();
jaroslav@597: T candidate = i.next();
jaroslav@597:
jaroslav@597: while (i.hasNext()) {
jaroslav@597: T next = i.next();
jaroslav@597: if (next.compareTo(candidate) > 0)
jaroslav@597: candidate = next;
jaroslav@597: }
jaroslav@597: return candidate;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns the maximum element of the given collection, according to the
jaroslav@597: * order induced by the specified comparator. All elements in the
jaroslav@597: * collection must be mutually comparable by the specified
jaroslav@597: * comparator (that is, comp.compare(e1, e2) must not throw a
jaroslav@597: * ClassCastException for any elements e1 and
jaroslav@597: * e2 in the collection).
jaroslav@597: *
jaroslav@597: * This method iterates over the entire collection, hence it requires
jaroslav@597: * time proportional to the size of the collection.
jaroslav@597: *
jaroslav@597: * @param coll the collection whose maximum element is to be determined.
jaroslav@597: * @param comp the comparator with which to determine the maximum element.
jaroslav@597: * A null value indicates that the elements' natural
jaroslav@597: * ordering should be used.
jaroslav@597: * @return the maximum element of the given collection, according
jaroslav@597: * to the specified comparator.
jaroslav@597: * @throws ClassCastException if the collection contains elements that are
jaroslav@597: * not mutually comparable using the specified comparator.
jaroslav@597: * @throws NoSuchElementException if the collection is empty.
jaroslav@597: * @see Comparable
jaroslav@597: */
jaroslav@597: public static T max(Collection coll, Comparator comp) {
jaroslav@597: if (comp==null)
jaroslav@597: return (T)max((Collection) (Collection) coll);
jaroslav@597:
jaroslav@597: Iterator i = coll.iterator();
jaroslav@597: T candidate = i.next();
jaroslav@597:
jaroslav@597: while (i.hasNext()) {
jaroslav@597: T next = i.next();
jaroslav@597: if (comp.compare(next, candidate) > 0)
jaroslav@597: candidate = next;
jaroslav@597: }
jaroslav@597: return candidate;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Rotates the elements in the specified list by the specified distance.
jaroslav@597: * After calling this method, the element at index i will be
jaroslav@597: * the element previously at index (i - distance) mod
jaroslav@597: * list.size(), for all values of i between 0
jaroslav@597: * and list.size()-1, inclusive. (This method has no effect on
jaroslav@597: * the size of the list.)
jaroslav@597: *
jaroslav@597: * For example, suppose list comprises [t, a, n, k, s].
jaroslav@597: * After invoking Collections.rotate(list, 1) (or
jaroslav@597: * Collections.rotate(list, -4)), list will comprise
jaroslav@597: * [s, t, a, n, k].
jaroslav@597: *
jaroslav@597: *
Note that this method can usefully be applied to sublists to
jaroslav@597: * move one or more elements within a list while preserving the
jaroslav@597: * order of the remaining elements. For example, the following idiom
jaroslav@597: * moves the element at index j forward to position
jaroslav@597: * k (which must be greater than or equal to j):
jaroslav@597: *
jaroslav@597: * Collections.rotate(list.subList(j, k+1), -1);
jaroslav@597: *
jaroslav@597: * To make this concrete, suppose list comprises
jaroslav@597: * [a, b, c, d, e]. To move the element at index 1
jaroslav@597: * (b) forward two positions, perform the following invocation:
jaroslav@597: *
jaroslav@597: * Collections.rotate(l.subList(1, 4), -1);
jaroslav@597: *
jaroslav@597: * The resulting list is [a, c, d, b, e].
jaroslav@597: *
jaroslav@597: * To move more than one element forward, increase the absolute value
jaroslav@597: * of the rotation distance. To move elements backward, use a positive
jaroslav@597: * shift distance.
jaroslav@597: *
jaroslav@597: *
If the specified list is small or implements the {@link
jaroslav@597: * RandomAccess} interface, this implementation exchanges the first
jaroslav@597: * element into the location it should go, and then repeatedly exchanges
jaroslav@597: * the displaced element into the location it should go until a displaced
jaroslav@597: * element is swapped into the first element. If necessary, the process
jaroslav@597: * is repeated on the second and successive elements, until the rotation
jaroslav@597: * is complete. If the specified list is large and doesn't implement the
jaroslav@597: * RandomAccess interface, this implementation breaks the
jaroslav@597: * list into two sublist views around index -distance mod size.
jaroslav@597: * Then the {@link #reverse(List)} method is invoked on each sublist view,
jaroslav@597: * and finally it is invoked on the entire list. For a more complete
jaroslav@597: * description of both algorithms, see Section 2.3 of Jon Bentley's
jaroslav@597: * Programming Pearls (Addison-Wesley, 1986).
jaroslav@597: *
jaroslav@597: * @param list the list to be rotated.
jaroslav@597: * @param distance the distance to rotate the list. There are no
jaroslav@597: * constraints on this value; it may be zero, negative, or
jaroslav@597: * greater than list.size().
jaroslav@597: * @throws UnsupportedOperationException if the specified list or
jaroslav@597: * its list-iterator does not support the set operation.
jaroslav@597: * @since 1.4
jaroslav@597: */
jaroslav@597: public static void rotate(List list, int distance) {
jaroslav@597: if (list instanceof RandomAccess || list.size() < ROTATE_THRESHOLD)
jaroslav@597: rotate1(list, distance);
jaroslav@597: else
jaroslav@597: rotate2(list, distance);
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static void rotate1(List list, int distance) {
jaroslav@597: int size = list.size();
jaroslav@597: if (size == 0)
jaroslav@597: return;
jaroslav@597: distance = distance % size;
jaroslav@597: if (distance < 0)
jaroslav@597: distance += size;
jaroslav@597: if (distance == 0)
jaroslav@597: return;
jaroslav@597:
jaroslav@597: for (int cycleStart = 0, nMoved = 0; nMoved != size; cycleStart++) {
jaroslav@597: T displaced = list.get(cycleStart);
jaroslav@597: int i = cycleStart;
jaroslav@597: do {
jaroslav@597: i += distance;
jaroslav@597: if (i >= size)
jaroslav@597: i -= size;
jaroslav@597: displaced = list.set(i, displaced);
jaroslav@597: nMoved ++;
jaroslav@597: } while (i != cycleStart);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static void rotate2(List list, int distance) {
jaroslav@597: int size = list.size();
jaroslav@597: if (size == 0)
jaroslav@597: return;
jaroslav@597: int mid = -distance % size;
jaroslav@597: if (mid < 0)
jaroslav@597: mid += size;
jaroslav@597: if (mid == 0)
jaroslav@597: return;
jaroslav@597:
jaroslav@597: reverse(list.subList(0, mid));
jaroslav@597: reverse(list.subList(mid, size));
jaroslav@597: reverse(list);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Replaces all occurrences of one specified value in a list with another.
jaroslav@597: * More formally, replaces with newVal each element e
jaroslav@597: * in list such that
jaroslav@597: * (oldVal==null ? e==null : oldVal.equals(e)).
jaroslav@597: * (This method has no effect on the size of the list.)
jaroslav@597: *
jaroslav@597: * @param list the list in which replacement is to occur.
jaroslav@597: * @param oldVal the old value to be replaced.
jaroslav@597: * @param newVal the new value with which oldVal is to be
jaroslav@597: * replaced.
jaroslav@597: * @return true if list contained one or more elements
jaroslav@597: * e such that
jaroslav@597: * (oldVal==null ? e==null : oldVal.equals(e)).
jaroslav@597: * @throws UnsupportedOperationException if the specified list or
jaroslav@597: * its list-iterator does not support the set operation.
jaroslav@597: * @since 1.4
jaroslav@597: */
jaroslav@597: public static boolean replaceAll(List list, T oldVal, T newVal) {
jaroslav@597: boolean result = false;
jaroslav@597: int size = list.size();
jaroslav@597: if (size < REPLACEALL_THRESHOLD || list instanceof RandomAccess) {
jaroslav@597: if (oldVal==null) {
jaroslav@597: for (int i=0; i itr=list.listIterator();
jaroslav@597: if (oldVal==null) {
jaroslav@597: for (int i=0; ii
jaroslav@597: * such that source.subList(i, i+target.size()).equals(target),
jaroslav@597: * or -1 if there is no such index. (Returns -1 if
jaroslav@597: * target.size() > source.size().)
jaroslav@597: *
jaroslav@597: * This implementation uses the "brute force" technique of scanning
jaroslav@597: * over the source list, looking for a match with the target at each
jaroslav@597: * location in turn.
jaroslav@597: *
jaroslav@597: * @param source the list in which to search for the first occurrence
jaroslav@597: * of target.
jaroslav@597: * @param target the list to search for as a subList of source.
jaroslav@597: * @return the starting position of the first occurrence of the specified
jaroslav@597: * target list within the specified source list, or -1 if there
jaroslav@597: * is no such occurrence.
jaroslav@597: * @since 1.4
jaroslav@597: */
jaroslav@597: public static int indexOfSubList(List source, List target) {
jaroslav@597: int sourceSize = source.size();
jaroslav@597: int targetSize = target.size();
jaroslav@597: int maxCandidate = sourceSize - targetSize;
jaroslav@597:
jaroslav@597: if (sourceSize < INDEXOFSUBLIST_THRESHOLD ||
jaroslav@597: (source instanceof RandomAccess&&target instanceof RandomAccess)) {
jaroslav@597: nextCand:
jaroslav@597: for (int candidate = 0; candidate <= maxCandidate; candidate++) {
jaroslav@597: for (int i=0, j=candidate; i si = source.listIterator();
jaroslav@597: nextCand:
jaroslav@597: for (int candidate = 0; candidate <= maxCandidate; candidate++) {
jaroslav@597: ListIterator ti = target.listIterator();
jaroslav@597: for (int i=0; ii
jaroslav@597: * such that source.subList(i, i+target.size()).equals(target),
jaroslav@597: * or -1 if there is no such index. (Returns -1 if
jaroslav@597: * target.size() > source.size().)
jaroslav@597: *
jaroslav@597: * This implementation uses the "brute force" technique of iterating
jaroslav@597: * over the source list, looking for a match with the target at each
jaroslav@597: * location in turn.
jaroslav@597: *
jaroslav@597: * @param source the list in which to search for the last occurrence
jaroslav@597: * of target.
jaroslav@597: * @param target the list to search for as a subList of source.
jaroslav@597: * @return the starting position of the last occurrence of the specified
jaroslav@597: * target list within the specified source list, or -1 if there
jaroslav@597: * is no such occurrence.
jaroslav@597: * @since 1.4
jaroslav@597: */
jaroslav@597: public static int lastIndexOfSubList(List source, List target) {
jaroslav@597: int sourceSize = source.size();
jaroslav@597: int targetSize = target.size();
jaroslav@597: int maxCandidate = sourceSize - targetSize;
jaroslav@597:
jaroslav@597: if (sourceSize < INDEXOFSUBLIST_THRESHOLD ||
jaroslav@597: source instanceof RandomAccess) { // Index access version
jaroslav@597: nextCand:
jaroslav@597: for (int candidate = maxCandidate; candidate >= 0; candidate--) {
jaroslav@597: for (int i=0, j=candidate; i si = source.listIterator(maxCandidate);
jaroslav@597: nextCand:
jaroslav@597: for (int candidate = maxCandidate; candidate >= 0; candidate--) {
jaroslav@597: ListIterator ti = target.listIterator();
jaroslav@597: for (int i=0; iUnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned collection does not pass the hashCode and equals
jaroslav@597: * operations through to the backing collection, but relies on
jaroslav@597: * Object's equals and hashCode methods. This
jaroslav@597: * is necessary to preserve the contracts of these operations in the case
jaroslav@597: * that the backing collection is a set or a list.
jaroslav@597: *
jaroslav@597: * The returned collection will be serializable if the specified collection
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param c the collection for which an unmodifiable view is to be
jaroslav@597: * returned.
jaroslav@597: * @return an unmodifiable view of the specified collection.
jaroslav@597: */
jaroslav@597: public static Collection unmodifiableCollection(Collection c) {
jaroslav@597: return new UnmodifiableCollection<>(c);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableCollection implements Collection, Serializable {
jaroslav@597: private static final long serialVersionUID = 1820017752578914078L;
jaroslav@597:
jaroslav@597: final Collection c;
jaroslav@597:
jaroslav@597: UnmodifiableCollection(Collection c) {
jaroslav@597: if (c==null)
jaroslav@597: throw new NullPointerException();
jaroslav@597: this.c = c;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int size() {return c.size();}
jaroslav@597: public boolean isEmpty() {return c.isEmpty();}
jaroslav@597: public boolean contains(Object o) {return c.contains(o);}
jaroslav@597: public Object[] toArray() {return c.toArray();}
jaroslav@597: public T[] toArray(T[] a) {return c.toArray(a);}
jaroslav@597: public String toString() {return c.toString();}
jaroslav@597:
jaroslav@597: public Iterator iterator() {
jaroslav@597: return new Iterator() {
jaroslav@597: private final Iterator i = c.iterator();
jaroslav@597:
jaroslav@597: public boolean hasNext() {return i.hasNext();}
jaroslav@597: public E next() {return i.next();}
jaroslav@597: public void remove() {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: };
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean add(E e) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public boolean remove(Object o) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean containsAll(Collection coll) {
jaroslav@597: return c.containsAll(coll);
jaroslav@597: }
jaroslav@597: public boolean addAll(Collection coll) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public boolean removeAll(Collection coll) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public boolean retainAll(Collection coll) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void clear() {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns an unmodifiable view of the specified set. This method allows
jaroslav@597: * modules to provide users with "read-only" access to internal sets.
jaroslav@597: * Query operations on the returned set "read through" to the specified
jaroslav@597: * set, and attempts to modify the returned set, whether direct or via its
jaroslav@597: * iterator, result in an UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned set will be serializable if the specified set
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param s the set for which an unmodifiable view is to be returned.
jaroslav@597: * @return an unmodifiable view of the specified set.
jaroslav@597: */
jaroslav@597: public static Set unmodifiableSet(Set s) {
jaroslav@597: return new UnmodifiableSet<>(s);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableSet extends UnmodifiableCollection
jaroslav@597: implements Set, Serializable {
jaroslav@597: private static final long serialVersionUID = -9215047833775013803L;
jaroslav@597:
jaroslav@597: UnmodifiableSet(Set s) {super(s);}
jaroslav@597: public boolean equals(Object o) {return o == this || c.equals(o);}
jaroslav@597: public int hashCode() {return c.hashCode();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns an unmodifiable view of the specified sorted set. This method
jaroslav@597: * allows modules to provide users with "read-only" access to internal
jaroslav@597: * sorted sets. Query operations on the returned sorted set "read
jaroslav@597: * through" to the specified sorted set. Attempts to modify the returned
jaroslav@597: * sorted set, whether direct, via its iterator, or via its
jaroslav@597: * subSet, headSet, or tailSet views, result in
jaroslav@597: * an UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned sorted set will be serializable if the specified sorted set
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param s the sorted set for which an unmodifiable view is to be
jaroslav@597: * returned.
jaroslav@597: * @return an unmodifiable view of the specified sorted set.
jaroslav@597: */
jaroslav@597: public static SortedSet unmodifiableSortedSet(SortedSet s) {
jaroslav@597: return new UnmodifiableSortedSet<>(s);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableSortedSet
jaroslav@597: extends UnmodifiableSet
jaroslav@597: implements SortedSet, Serializable {
jaroslav@597: private static final long serialVersionUID = -4929149591599911165L;
jaroslav@597: private final SortedSet ss;
jaroslav@597:
jaroslav@597: UnmodifiableSortedSet(SortedSet s) {super(s); ss = s;}
jaroslav@597:
jaroslav@597: public Comparator comparator() {return ss.comparator();}
jaroslav@597:
jaroslav@597: public SortedSet subSet(E fromElement, E toElement) {
jaroslav@597: return new UnmodifiableSortedSet<>(ss.subSet(fromElement,toElement));
jaroslav@597: }
jaroslav@597: public SortedSet headSet(E toElement) {
jaroslav@597: return new UnmodifiableSortedSet<>(ss.headSet(toElement));
jaroslav@597: }
jaroslav@597: public SortedSet tailSet(E fromElement) {
jaroslav@597: return new UnmodifiableSortedSet<>(ss.tailSet(fromElement));
jaroslav@597: }
jaroslav@597:
jaroslav@597: public E first() {return ss.first();}
jaroslav@597: public E last() {return ss.last();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns an unmodifiable view of the specified list. This method allows
jaroslav@597: * modules to provide users with "read-only" access to internal
jaroslav@597: * lists. Query operations on the returned list "read through" to the
jaroslav@597: * specified list, and attempts to modify the returned list, whether
jaroslav@597: * direct or via its iterator, result in an
jaroslav@597: * UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned list will be serializable if the specified list
jaroslav@597: * is serializable. Similarly, the returned list will implement
jaroslav@597: * {@link RandomAccess} if the specified list does.
jaroslav@597: *
jaroslav@597: * @param list the list for which an unmodifiable view is to be returned.
jaroslav@597: * @return an unmodifiable view of the specified list.
jaroslav@597: */
jaroslav@597: public static List unmodifiableList(List list) {
jaroslav@597: return (list instanceof RandomAccess ?
jaroslav@597: new UnmodifiableRandomAccessList<>(list) :
jaroslav@597: new UnmodifiableList<>(list));
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableList extends UnmodifiableCollection
jaroslav@597: implements List {
jaroslav@597: private static final long serialVersionUID = -283967356065247728L;
jaroslav@597: final List list;
jaroslav@597:
jaroslav@597: UnmodifiableList(List list) {
jaroslav@597: super(list);
jaroslav@597: this.list = list;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) {return o == this || list.equals(o);}
jaroslav@597: public int hashCode() {return list.hashCode();}
jaroslav@597:
jaroslav@597: public E get(int index) {return list.get(index);}
jaroslav@597: public E set(int index, E element) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void add(int index, E element) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public E remove(int index) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public int indexOf(Object o) {return list.indexOf(o);}
jaroslav@597: public int lastIndexOf(Object o) {return list.lastIndexOf(o);}
jaroslav@597: public boolean addAll(int index, Collection c) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public ListIterator listIterator() {return listIterator(0);}
jaroslav@597:
jaroslav@597: public ListIterator listIterator(final int index) {
jaroslav@597: return new ListIterator() {
jaroslav@597: private final ListIterator i
jaroslav@597: = list.listIterator(index);
jaroslav@597:
jaroslav@597: public boolean hasNext() {return i.hasNext();}
jaroslav@597: public E next() {return i.next();}
jaroslav@597: public boolean hasPrevious() {return i.hasPrevious();}
jaroslav@597: public E previous() {return i.previous();}
jaroslav@597: public int nextIndex() {return i.nextIndex();}
jaroslav@597: public int previousIndex() {return i.previousIndex();}
jaroslav@597:
jaroslav@597: public void remove() {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void set(E e) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void add(E e) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: };
jaroslav@597: }
jaroslav@597:
jaroslav@597: public List subList(int fromIndex, int toIndex) {
jaroslav@597: return new UnmodifiableList<>(list.subList(fromIndex, toIndex));
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * UnmodifiableRandomAccessList instances are serialized as
jaroslav@597: * UnmodifiableList instances to allow them to be deserialized
jaroslav@597: * in pre-1.4 JREs (which do not have UnmodifiableRandomAccessList).
jaroslav@597: * This method inverts the transformation. As a beneficial
jaroslav@597: * side-effect, it also grafts the RandomAccess marker onto
jaroslav@597: * UnmodifiableList instances that were serialized in pre-1.4 JREs.
jaroslav@597: *
jaroslav@597: * Note: Unfortunately, UnmodifiableRandomAccessList instances
jaroslav@597: * serialized in 1.4.1 and deserialized in 1.4 will become
jaroslav@597: * UnmodifiableList instances, as this method was missing in 1.4.
jaroslav@597: */
jaroslav@597: private Object readResolve() {
jaroslav@597: return (list instanceof RandomAccess
jaroslav@597: ? new UnmodifiableRandomAccessList<>(list)
jaroslav@597: : this);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableRandomAccessList extends UnmodifiableList
jaroslav@597: implements RandomAccess
jaroslav@597: {
jaroslav@597: UnmodifiableRandomAccessList(List list) {
jaroslav@597: super(list);
jaroslav@597: }
jaroslav@597:
jaroslav@597: public List subList(int fromIndex, int toIndex) {
jaroslav@597: return new UnmodifiableRandomAccessList<>(
jaroslav@597: list.subList(fromIndex, toIndex));
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static final long serialVersionUID = -2542308836966382001L;
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Allows instances to be deserialized in pre-1.4 JREs (which do
jaroslav@597: * not have UnmodifiableRandomAccessList). UnmodifiableList has
jaroslav@597: * a readResolve method that inverts this transformation upon
jaroslav@597: * deserialization.
jaroslav@597: */
jaroslav@597: private Object writeReplace() {
jaroslav@597: return new UnmodifiableList<>(list);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns an unmodifiable view of the specified map. This method
jaroslav@597: * allows modules to provide users with "read-only" access to internal
jaroslav@597: * maps. Query operations on the returned map "read through"
jaroslav@597: * to the specified map, and attempts to modify the returned
jaroslav@597: * map, whether direct or via its collection views, result in an
jaroslav@597: * UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned map will be serializable if the specified map
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param m the map for which an unmodifiable view is to be returned.
jaroslav@597: * @return an unmodifiable view of the specified map.
jaroslav@597: */
jaroslav@597: public static Map unmodifiableMap(Map m) {
jaroslav@597: return new UnmodifiableMap<>(m);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: private static class UnmodifiableMap implements Map, Serializable {
jaroslav@597: private static final long serialVersionUID = -1034234728574286014L;
jaroslav@597:
jaroslav@597: private final Map m;
jaroslav@597:
jaroslav@597: UnmodifiableMap(Map m) {
jaroslav@597: if (m==null)
jaroslav@597: throw new NullPointerException();
jaroslav@597: this.m = m;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int size() {return m.size();}
jaroslav@597: public boolean isEmpty() {return m.isEmpty();}
jaroslav@597: public boolean containsKey(Object key) {return m.containsKey(key);}
jaroslav@597: public boolean containsValue(Object val) {return m.containsValue(val);}
jaroslav@597: public V get(Object key) {return m.get(key);}
jaroslav@597:
jaroslav@597: public V put(K key, V value) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public V remove(Object key) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void putAll(Map m) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public void clear() {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597:
jaroslav@597: private transient Set keySet = null;
jaroslav@597: private transient Set> entrySet = null;
jaroslav@597: private transient Collection values = null;
jaroslav@597:
jaroslav@597: public Set keySet() {
jaroslav@597: if (keySet==null)
jaroslav@597: keySet = unmodifiableSet(m.keySet());
jaroslav@597: return keySet;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Set> entrySet() {
jaroslav@597: if (entrySet==null)
jaroslav@597: entrySet = new UnmodifiableEntrySet<>(m.entrySet());
jaroslav@597: return entrySet;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Collection values() {
jaroslav@597: if (values==null)
jaroslav@597: values = unmodifiableCollection(m.values());
jaroslav@597: return values;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) {return o == this || m.equals(o);}
jaroslav@597: public int hashCode() {return m.hashCode();}
jaroslav@597: public String toString() {return m.toString();}
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * We need this class in addition to UnmodifiableSet as
jaroslav@597: * Map.Entries themselves permit modification of the backing Map
jaroslav@597: * via their setValue operation. This class is subtle: there are
jaroslav@597: * many possible attacks that must be thwarted.
jaroslav@597: *
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableEntrySet
jaroslav@597: extends UnmodifiableSet> {
jaroslav@597: private static final long serialVersionUID = 7854390611657943733L;
jaroslav@597:
jaroslav@597: UnmodifiableEntrySet(Set> s) {
jaroslav@597: super((Set)s);
jaroslav@597: }
jaroslav@597: public Iterator> iterator() {
jaroslav@597: return new Iterator>() {
jaroslav@597: private final Iterator> i = c.iterator();
jaroslav@597:
jaroslav@597: public boolean hasNext() {
jaroslav@597: return i.hasNext();
jaroslav@597: }
jaroslav@597: public Map.Entry next() {
jaroslav@597: return new UnmodifiableEntry<>(i.next());
jaroslav@597: }
jaroslav@597: public void remove() {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: };
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Object[] toArray() {
jaroslav@597: Object[] a = c.toArray();
jaroslav@597: for (int i=0; i((Map.Entry)a[i]);
jaroslav@597: return a;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public T[] toArray(T[] a) {
jaroslav@597: // We don't pass a to c.toArray, to avoid window of
jaroslav@597: // vulnerability wherein an unscrupulous multithreaded client
jaroslav@597: // could get his hands on raw (unwrapped) Entries from c.
jaroslav@597: Object[] arr = c.toArray(a.length==0 ? a : Arrays.copyOf(a, 0));
jaroslav@597:
jaroslav@597: for (int i=0; i((Map.Entry)arr[i]);
jaroslav@597:
jaroslav@597: if (arr.length > a.length)
jaroslav@597: return (T[])arr;
jaroslav@597:
jaroslav@597: System.arraycopy(arr, 0, a, 0, arr.length);
jaroslav@597: if (a.length > arr.length)
jaroslav@597: a[arr.length] = null;
jaroslav@597: return a;
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * This method is overridden to protect the backing set against
jaroslav@597: * an object with a nefarious equals function that senses
jaroslav@597: * that the equality-candidate is Map.Entry and calls its
jaroslav@597: * setValue method.
jaroslav@597: */
jaroslav@597: public boolean contains(Object o) {
jaroslav@597: if (!(o instanceof Map.Entry))
jaroslav@597: return false;
jaroslav@597: return c.contains(
jaroslav@597: new UnmodifiableEntry<>((Map.Entry) o));
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * The next two methods are overridden to protect against
jaroslav@597: * an unscrupulous List whose contains(Object o) method senses
jaroslav@597: * when o is a Map.Entry, and calls o.setValue.
jaroslav@597: */
jaroslav@597: public boolean containsAll(Collection coll) {
jaroslav@597: for (Object e : coll) {
jaroslav@597: if (!contains(e)) // Invokes safe contains() above
jaroslav@597: return false;
jaroslav@597: }
jaroslav@597: return true;
jaroslav@597: }
jaroslav@597: public boolean equals(Object o) {
jaroslav@597: if (o == this)
jaroslav@597: return true;
jaroslav@597:
jaroslav@597: if (!(o instanceof Set))
jaroslav@597: return false;
jaroslav@597: Set s = (Set) o;
jaroslav@597: if (s.size() != c.size())
jaroslav@597: return false;
jaroslav@597: return containsAll(s); // Invokes safe containsAll() above
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * This "wrapper class" serves two purposes: it prevents
jaroslav@597: * the client from modifying the backing Map, by short-circuiting
jaroslav@597: * the setValue method, and it protects the backing Map against
jaroslav@597: * an ill-behaved Map.Entry that attempts to modify another
jaroslav@597: * Map Entry when asked to perform an equality check.
jaroslav@597: */
jaroslav@597: private static class UnmodifiableEntry implements Map.Entry {
jaroslav@597: private Map.Entry e;
jaroslav@597:
jaroslav@597: UnmodifiableEntry(Map.Entry e) {this.e = e;}
jaroslav@597:
jaroslav@597: public K getKey() {return e.getKey();}
jaroslav@597: public V getValue() {return e.getValue();}
jaroslav@597: public V setValue(V value) {
jaroslav@597: throw new UnsupportedOperationException();
jaroslav@597: }
jaroslav@597: public int hashCode() {return e.hashCode();}
jaroslav@597: public boolean equals(Object o) {
jaroslav@597: if (!(o instanceof Map.Entry))
jaroslav@597: return false;
jaroslav@597: Map.Entry t = (Map.Entry)o;
jaroslav@597: return eq(e.getKey(), t.getKey()) &&
jaroslav@597: eq(e.getValue(), t.getValue());
jaroslav@597: }
jaroslav@597: public String toString() {return e.toString();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns an unmodifiable view of the specified sorted map. This method
jaroslav@597: * allows modules to provide users with "read-only" access to internal
jaroslav@597: * sorted maps. Query operations on the returned sorted map "read through"
jaroslav@597: * to the specified sorted map. Attempts to modify the returned
jaroslav@597: * sorted map, whether direct, via its collection views, or via its
jaroslav@597: * subMap, headMap, or tailMap views, result in
jaroslav@597: * an UnsupportedOperationException.
jaroslav@597: *
jaroslav@597: * The returned sorted map will be serializable if the specified sorted map
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param m the sorted map for which an unmodifiable view is to be
jaroslav@597: * returned.
jaroslav@597: * @return an unmodifiable view of the specified sorted map.
jaroslav@597: */
jaroslav@597: public static SortedMap unmodifiableSortedMap(SortedMap m) {
jaroslav@597: return new UnmodifiableSortedMap<>(m);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class UnmodifiableSortedMap
jaroslav@597: extends UnmodifiableMap
jaroslav@597: implements SortedMap, Serializable {
jaroslav@597: private static final long serialVersionUID = -8806743815996713206L;
jaroslav@597:
jaroslav@597: private final SortedMap sm;
jaroslav@597:
jaroslav@597: UnmodifiableSortedMap(SortedMap m) {super(m); sm = m;}
jaroslav@597:
jaroslav@597: public Comparator comparator() {return sm.comparator();}
jaroslav@597:
jaroslav@597: public SortedMap subMap(K fromKey, K toKey) {
jaroslav@597: return new UnmodifiableSortedMap<>(sm.subMap(fromKey, toKey));
jaroslav@597: }
jaroslav@597: public SortedMap headMap(K toKey) {
jaroslav@597: return new UnmodifiableSortedMap<>(sm.headMap(toKey));
jaroslav@597: }
jaroslav@597: public SortedMap tailMap(K fromKey) {
jaroslav@597: return new UnmodifiableSortedMap<>(sm.tailMap(fromKey));
jaroslav@597: }
jaroslav@597:
jaroslav@597: public K firstKey() {return sm.firstKey();}
jaroslav@597: public K lastKey() {return sm.lastKey();}
jaroslav@597: }
jaroslav@597:
jaroslav@597:
jaroslav@597: // Synch Wrappers
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) collection backed by the specified
jaroslav@597: * collection. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing collection is accomplished
jaroslav@597: * through the returned collection.
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * collection when iterating over it:
jaroslav@597: *
jaroslav@597: * Collection c = Collections.synchronizedCollection(myCollection);
jaroslav@597: * ...
jaroslav@597: * synchronized (c) {
jaroslav@597: * Iterator i = c.iterator(); // Must be in the synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned collection does not pass the hashCode
jaroslav@597: * and equals operations through to the backing collection, but
jaroslav@597: * relies on Object's equals and hashCode methods. This is
jaroslav@597: * necessary to preserve the contracts of these operations in the case
jaroslav@597: * that the backing collection is a set or a list.
jaroslav@597: *
jaroslav@597: * The returned collection will be serializable if the specified collection
jaroslav@597: * is serializable.
jaroslav@597: *
jaroslav@597: * @param c the collection to be "wrapped" in a synchronized collection.
jaroslav@597: * @return a synchronized view of the specified collection.
jaroslav@597: */
jaroslav@597: public static Collection synchronizedCollection(Collection c) {
jaroslav@597: return new SynchronizedCollection<>(c);
jaroslav@597: }
jaroslav@597:
jaroslav@597: static Collection synchronizedCollection(Collection c, Object mutex) {
jaroslav@597: return new SynchronizedCollection<>(c, mutex);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedCollection implements Collection, Serializable {
jaroslav@597: private static final long serialVersionUID = 3053995032091335093L;
jaroslav@597:
jaroslav@597: final Collection c; // Backing Collection
jaroslav@597: final Object mutex; // Object on which to synchronize
jaroslav@597:
jaroslav@597: SynchronizedCollection(Collection c) {
jaroslav@597: if (c==null)
jaroslav@597: throw new NullPointerException();
jaroslav@597: this.c = c;
jaroslav@597: mutex = this;
jaroslav@597: }
jaroslav@597: SynchronizedCollection(Collection c, Object mutex) {
jaroslav@597: this.c = c;
jaroslav@597: this.mutex = mutex;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int size() {
jaroslav@597: synchronized (mutex) {return c.size();}
jaroslav@597: }
jaroslav@597: public boolean isEmpty() {
jaroslav@597: synchronized (mutex) {return c.isEmpty();}
jaroslav@597: }
jaroslav@597: public boolean contains(Object o) {
jaroslav@597: synchronized (mutex) {return c.contains(o);}
jaroslav@597: }
jaroslav@597: public Object[] toArray() {
jaroslav@597: synchronized (mutex) {return c.toArray();}
jaroslav@597: }
jaroslav@597: public T[] toArray(T[] a) {
jaroslav@597: synchronized (mutex) {return c.toArray(a);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Iterator iterator() {
jaroslav@597: return c.iterator(); // Must be manually synched by user!
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean add(E e) {
jaroslav@597: synchronized (mutex) {return c.add(e);}
jaroslav@597: }
jaroslav@597: public boolean remove(Object o) {
jaroslav@597: synchronized (mutex) {return c.remove(o);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean containsAll(Collection coll) {
jaroslav@597: synchronized (mutex) {return c.containsAll(coll);}
jaroslav@597: }
jaroslav@597: public boolean addAll(Collection coll) {
jaroslav@597: synchronized (mutex) {return c.addAll(coll);}
jaroslav@597: }
jaroslav@597: public boolean removeAll(Collection coll) {
jaroslav@597: synchronized (mutex) {return c.removeAll(coll);}
jaroslav@597: }
jaroslav@597: public boolean retainAll(Collection coll) {
jaroslav@597: synchronized (mutex) {return c.retainAll(coll);}
jaroslav@597: }
jaroslav@597: public void clear() {
jaroslav@597: synchronized (mutex) {c.clear();}
jaroslav@597: }
jaroslav@597: public String toString() {
jaroslav@597: synchronized (mutex) {return c.toString();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) set backed by the specified
jaroslav@597: * set. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing set is accomplished
jaroslav@597: * through the returned set.
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * set when iterating over it:
jaroslav@597: *
jaroslav@597: * Set s = Collections.synchronizedSet(new HashSet());
jaroslav@597: * ...
jaroslav@597: * synchronized (s) {
jaroslav@597: * Iterator i = s.iterator(); // Must be in the synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned set will be serializable if the specified set is
jaroslav@597: * serializable.
jaroslav@597: *
jaroslav@597: * @param s the set to be "wrapped" in a synchronized set.
jaroslav@597: * @return a synchronized view of the specified set.
jaroslav@597: */
jaroslav@597: public static Set synchronizedSet(Set s) {
jaroslav@597: return new SynchronizedSet<>(s);
jaroslav@597: }
jaroslav@597:
jaroslav@597: static Set synchronizedSet(Set s, Object mutex) {
jaroslav@597: return new SynchronizedSet<>(s, mutex);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedSet
jaroslav@597: extends SynchronizedCollection
jaroslav@597: implements Set {
jaroslav@597: private static final long serialVersionUID = 487447009682186044L;
jaroslav@597:
jaroslav@597: SynchronizedSet(Set s) {
jaroslav@597: super(s);
jaroslav@597: }
jaroslav@597: SynchronizedSet(Set s, Object mutex) {
jaroslav@597: super(s, mutex);
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) {
jaroslav@597: synchronized (mutex) {return c.equals(o);}
jaroslav@597: }
jaroslav@597: public int hashCode() {
jaroslav@597: synchronized (mutex) {return c.hashCode();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) sorted set backed by the specified
jaroslav@597: * sorted set. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing sorted set is accomplished
jaroslav@597: * through the returned sorted set (or its views).
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * sorted set when iterating over it or any of its subSet,
jaroslav@597: * headSet, or tailSet views.
jaroslav@597: *
jaroslav@597: * SortedSet s = Collections.synchronizedSortedSet(new TreeSet());
jaroslav@597: * ...
jaroslav@597: * synchronized (s) {
jaroslav@597: * Iterator i = s.iterator(); // Must be in the synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * or:
jaroslav@597: *
jaroslav@597: * SortedSet s = Collections.synchronizedSortedSet(new TreeSet());
jaroslav@597: * SortedSet s2 = s.headSet(foo);
jaroslav@597: * ...
jaroslav@597: * synchronized (s) { // Note: s, not s2!!!
jaroslav@597: * Iterator i = s2.iterator(); // Must be in the synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned sorted set will be serializable if the specified
jaroslav@597: * sorted set is serializable.
jaroslav@597: *
jaroslav@597: * @param s the sorted set to be "wrapped" in a synchronized sorted set.
jaroslav@597: * @return a synchronized view of the specified sorted set.
jaroslav@597: */
jaroslav@597: public static SortedSet synchronizedSortedSet(SortedSet s) {
jaroslav@597: return new SynchronizedSortedSet<>(s);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedSortedSet
jaroslav@597: extends SynchronizedSet
jaroslav@597: implements SortedSet
jaroslav@597: {
jaroslav@597: private static final long serialVersionUID = 8695801310862127406L;
jaroslav@597:
jaroslav@597: private final SortedSet ss;
jaroslav@597:
jaroslav@597: SynchronizedSortedSet(SortedSet s) {
jaroslav@597: super(s);
jaroslav@597: ss = s;
jaroslav@597: }
jaroslav@597: SynchronizedSortedSet(SortedSet s, Object mutex) {
jaroslav@597: super(s, mutex);
jaroslav@597: ss = s;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Comparator comparator() {
jaroslav@597: synchronized (mutex) {return ss.comparator();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public SortedSet subSet(E fromElement, E toElement) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedSet<>(
jaroslav@597: ss.subSet(fromElement, toElement), mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597: public SortedSet headSet(E toElement) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedSet<>(ss.headSet(toElement), mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597: public SortedSet tailSet(E fromElement) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedSet<>(ss.tailSet(fromElement),mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: public E first() {
jaroslav@597: synchronized (mutex) {return ss.first();}
jaroslav@597: }
jaroslav@597: public E last() {
jaroslav@597: synchronized (mutex) {return ss.last();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) list backed by the specified
jaroslav@597: * list. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing list is accomplished
jaroslav@597: * through the returned list.
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * list when iterating over it:
jaroslav@597: *
jaroslav@597: * List list = Collections.synchronizedList(new ArrayList());
jaroslav@597: * ...
jaroslav@597: * synchronized (list) {
jaroslav@597: * Iterator i = list.iterator(); // Must be in synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned list will be serializable if the specified list is
jaroslav@597: * serializable.
jaroslav@597: *
jaroslav@597: * @param list the list to be "wrapped" in a synchronized list.
jaroslav@597: * @return a synchronized view of the specified list.
jaroslav@597: */
jaroslav@597: public static List synchronizedList(List list) {
jaroslav@597: return (list instanceof RandomAccess ?
jaroslav@597: new SynchronizedRandomAccessList<>(list) :
jaroslav@597: new SynchronizedList<>(list));
jaroslav@597: }
jaroslav@597:
jaroslav@597: static List synchronizedList(List list, Object mutex) {
jaroslav@597: return (list instanceof RandomAccess ?
jaroslav@597: new SynchronizedRandomAccessList<>(list, mutex) :
jaroslav@597: new SynchronizedList<>(list, mutex));
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedList
jaroslav@597: extends SynchronizedCollection
jaroslav@597: implements List {
jaroslav@597: private static final long serialVersionUID = -7754090372962971524L;
jaroslav@597:
jaroslav@597: final List list;
jaroslav@597:
jaroslav@597: SynchronizedList(List list) {
jaroslav@597: super(list);
jaroslav@597: this.list = list;
jaroslav@597: }
jaroslav@597: SynchronizedList(List list, Object mutex) {
jaroslav@597: super(list, mutex);
jaroslav@597: this.list = list;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) {
jaroslav@597: synchronized (mutex) {return list.equals(o);}
jaroslav@597: }
jaroslav@597: public int hashCode() {
jaroslav@597: synchronized (mutex) {return list.hashCode();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public E get(int index) {
jaroslav@597: synchronized (mutex) {return list.get(index);}
jaroslav@597: }
jaroslav@597: public E set(int index, E element) {
jaroslav@597: synchronized (mutex) {return list.set(index, element);}
jaroslav@597: }
jaroslav@597: public void add(int index, E element) {
jaroslav@597: synchronized (mutex) {list.add(index, element);}
jaroslav@597: }
jaroslav@597: public E remove(int index) {
jaroslav@597: synchronized (mutex) {return list.remove(index);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int indexOf(Object o) {
jaroslav@597: synchronized (mutex) {return list.indexOf(o);}
jaroslav@597: }
jaroslav@597: public int lastIndexOf(Object o) {
jaroslav@597: synchronized (mutex) {return list.lastIndexOf(o);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean addAll(int index, Collection c) {
jaroslav@597: synchronized (mutex) {return list.addAll(index, c);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public ListIterator listIterator() {
jaroslav@597: return list.listIterator(); // Must be manually synched by user
jaroslav@597: }
jaroslav@597:
jaroslav@597: public ListIterator listIterator(int index) {
jaroslav@597: return list.listIterator(index); // Must be manually synched by user
jaroslav@597: }
jaroslav@597:
jaroslav@597: public List subList(int fromIndex, int toIndex) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedList<>(list.subList(fromIndex, toIndex),
jaroslav@597: mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * SynchronizedRandomAccessList instances are serialized as
jaroslav@597: * SynchronizedList instances to allow them to be deserialized
jaroslav@597: * in pre-1.4 JREs (which do not have SynchronizedRandomAccessList).
jaroslav@597: * This method inverts the transformation. As a beneficial
jaroslav@597: * side-effect, it also grafts the RandomAccess marker onto
jaroslav@597: * SynchronizedList instances that were serialized in pre-1.4 JREs.
jaroslav@597: *
jaroslav@597: * Note: Unfortunately, SynchronizedRandomAccessList instances
jaroslav@597: * serialized in 1.4.1 and deserialized in 1.4 will become
jaroslav@597: * SynchronizedList instances, as this method was missing in 1.4.
jaroslav@597: */
jaroslav@597: private Object readResolve() {
jaroslav@597: return (list instanceof RandomAccess
jaroslav@597: ? new SynchronizedRandomAccessList<>(list)
jaroslav@597: : this);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedRandomAccessList
jaroslav@597: extends SynchronizedList
jaroslav@597: implements RandomAccess {
jaroslav@597:
jaroslav@597: SynchronizedRandomAccessList(List list) {
jaroslav@597: super(list);
jaroslav@597: }
jaroslav@597:
jaroslav@597: SynchronizedRandomAccessList(List list, Object mutex) {
jaroslav@597: super(list, mutex);
jaroslav@597: }
jaroslav@597:
jaroslav@597: public List subList(int fromIndex, int toIndex) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedRandomAccessList<>(
jaroslav@597: list.subList(fromIndex, toIndex), mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: private static final long serialVersionUID = 1530674583602358482L;
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Allows instances to be deserialized in pre-1.4 JREs (which do
jaroslav@597: * not have SynchronizedRandomAccessList). SynchronizedList has
jaroslav@597: * a readResolve method that inverts this transformation upon
jaroslav@597: * deserialization.
jaroslav@597: */
jaroslav@597: private Object writeReplace() {
jaroslav@597: return new SynchronizedList<>(list);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) map backed by the specified
jaroslav@597: * map. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing map is accomplished
jaroslav@597: * through the returned map.
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * map when iterating over any of its collection views:
jaroslav@597: *
jaroslav@597: * Map m = Collections.synchronizedMap(new HashMap());
jaroslav@597: * ...
jaroslav@597: * Set s = m.keySet(); // Needn't be in synchronized block
jaroslav@597: * ...
jaroslav@597: * synchronized (m) { // Synchronizing on m, not s!
jaroslav@597: * Iterator i = s.iterator(); // Must be in synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned map will be serializable if the specified map is
jaroslav@597: * serializable.
jaroslav@597: *
jaroslav@597: * @param m the map to be "wrapped" in a synchronized map.
jaroslav@597: * @return a synchronized view of the specified map.
jaroslav@597: */
jaroslav@597: public static Map synchronizedMap(Map m) {
jaroslav@597: return new SynchronizedMap<>(m);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: private static class SynchronizedMap
jaroslav@597: implements Map, Serializable {
jaroslav@597: private static final long serialVersionUID = 1978198479659022715L;
jaroslav@597:
jaroslav@597: private final Map m; // Backing Map
jaroslav@597: final Object mutex; // Object on which to synchronize
jaroslav@597:
jaroslav@597: SynchronizedMap(Map m) {
jaroslav@597: if (m==null)
jaroslav@597: throw new NullPointerException();
jaroslav@597: this.m = m;
jaroslav@597: mutex = this;
jaroslav@597: }
jaroslav@597:
jaroslav@597: SynchronizedMap(Map m, Object mutex) {
jaroslav@597: this.m = m;
jaroslav@597: this.mutex = mutex;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int size() {
jaroslav@597: synchronized (mutex) {return m.size();}
jaroslav@597: }
jaroslav@597: public boolean isEmpty() {
jaroslav@597: synchronized (mutex) {return m.isEmpty();}
jaroslav@597: }
jaroslav@597: public boolean containsKey(Object key) {
jaroslav@597: synchronized (mutex) {return m.containsKey(key);}
jaroslav@597: }
jaroslav@597: public boolean containsValue(Object value) {
jaroslav@597: synchronized (mutex) {return m.containsValue(value);}
jaroslav@597: }
jaroslav@597: public V get(Object key) {
jaroslav@597: synchronized (mutex) {return m.get(key);}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public V put(K key, V value) {
jaroslav@597: synchronized (mutex) {return m.put(key, value);}
jaroslav@597: }
jaroslav@597: public V remove(Object key) {
jaroslav@597: synchronized (mutex) {return m.remove(key);}
jaroslav@597: }
jaroslav@597: public void putAll(Map map) {
jaroslav@597: synchronized (mutex) {m.putAll(map);}
jaroslav@597: }
jaroslav@597: public void clear() {
jaroslav@597: synchronized (mutex) {m.clear();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: private transient Set keySet = null;
jaroslav@597: private transient Set> entrySet = null;
jaroslav@597: private transient Collection values = null;
jaroslav@597:
jaroslav@597: public Set keySet() {
jaroslav@597: synchronized (mutex) {
jaroslav@597: if (keySet==null)
jaroslav@597: keySet = new SynchronizedSet<>(m.keySet(), mutex);
jaroslav@597: return keySet;
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Set> entrySet() {
jaroslav@597: synchronized (mutex) {
jaroslav@597: if (entrySet==null)
jaroslav@597: entrySet = new SynchronizedSet<>(m.entrySet(), mutex);
jaroslav@597: return entrySet;
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Collection values() {
jaroslav@597: synchronized (mutex) {
jaroslav@597: if (values==null)
jaroslav@597: values = new SynchronizedCollection<>(m.values(), mutex);
jaroslav@597: return values;
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) {
jaroslav@597: synchronized (mutex) {return m.equals(o);}
jaroslav@597: }
jaroslav@597: public int hashCode() {
jaroslav@597: synchronized (mutex) {return m.hashCode();}
jaroslav@597: }
jaroslav@597: public String toString() {
jaroslav@597: synchronized (mutex) {return m.toString();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a synchronized (thread-safe) sorted map backed by the specified
jaroslav@597: * sorted map. In order to guarantee serial access, it is critical that
jaroslav@597: * all access to the backing sorted map is accomplished
jaroslav@597: * through the returned sorted map (or its views).
jaroslav@597: *
jaroslav@597: * It is imperative that the user manually synchronize on the returned
jaroslav@597: * sorted map when iterating over any of its collection views, or the
jaroslav@597: * collections views of any of its subMap, headMap or
jaroslav@597: * tailMap views.
jaroslav@597: *
jaroslav@597: * SortedMap m = Collections.synchronizedSortedMap(new TreeMap());
jaroslav@597: * ...
jaroslav@597: * Set s = m.keySet(); // Needn't be in synchronized block
jaroslav@597: * ...
jaroslav@597: * synchronized (m) { // Synchronizing on m, not s!
jaroslav@597: * Iterator i = s.iterator(); // Must be in synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * or:
jaroslav@597: *
jaroslav@597: * SortedMap m = Collections.synchronizedSortedMap(new TreeMap());
jaroslav@597: * SortedMap m2 = m.subMap(foo, bar);
jaroslav@597: * ...
jaroslav@597: * Set s2 = m2.keySet(); // Needn't be in synchronized block
jaroslav@597: * ...
jaroslav@597: * synchronized (m) { // Synchronizing on m, not m2 or s2!
jaroslav@597: * Iterator i = s.iterator(); // Must be in synchronized block
jaroslav@597: * while (i.hasNext())
jaroslav@597: * foo(i.next());
jaroslav@597: * }
jaroslav@597: *
jaroslav@597: * Failure to follow this advice may result in non-deterministic behavior.
jaroslav@597: *
jaroslav@597: * The returned sorted map will be serializable if the specified
jaroslav@597: * sorted map is serializable.
jaroslav@597: *
jaroslav@597: * @param m the sorted map to be "wrapped" in a synchronized sorted map.
jaroslav@597: * @return a synchronized view of the specified sorted map.
jaroslav@597: */
jaroslav@597: public static SortedMap synchronizedSortedMap(SortedMap m) {
jaroslav@597: return new SynchronizedSortedMap<>(m);
jaroslav@597: }
jaroslav@597:
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class SynchronizedSortedMap
jaroslav@597: extends SynchronizedMap
jaroslav@597: implements SortedMap
jaroslav@597: {
jaroslav@597: private static final long serialVersionUID = -8798146769416483793L;
jaroslav@597:
jaroslav@597: private final SortedMap sm;
jaroslav@597:
jaroslav@597: SynchronizedSortedMap(SortedMap m) {
jaroslav@597: super(m);
jaroslav@597: sm = m;
jaroslav@597: }
jaroslav@597: SynchronizedSortedMap(SortedMap m, Object mutex) {
jaroslav@597: super(m, mutex);
jaroslav@597: sm = m;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Comparator comparator() {
jaroslav@597: synchronized (mutex) {return sm.comparator();}
jaroslav@597: }
jaroslav@597:
jaroslav@597: public SortedMap subMap(K fromKey, K toKey) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedMap<>(
jaroslav@597: sm.subMap(fromKey, toKey), mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597: public SortedMap headMap(K toKey) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedMap<>(sm.headMap(toKey), mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597: public SortedMap tailMap(K fromKey) {
jaroslav@597: synchronized (mutex) {
jaroslav@597: return new SynchronizedSortedMap<>(sm.tailMap(fromKey),mutex);
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: public K firstKey() {
jaroslav@597: synchronized (mutex) {return sm.firstKey();}
jaroslav@597: }
jaroslav@597: public K lastKey() {
jaroslav@597: synchronized (mutex) {return sm.lastKey();}
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: // Dynamically typesafe collection wrappers
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a dynamically typesafe view of the specified collection.
jaroslav@597: * Any attempt to insert an element of the wrong type will result in an
jaroslav@597: * immediate {@link ClassCastException}. Assuming a collection
jaroslav@597: * contains no incorrectly typed elements prior to the time a
jaroslav@597: * dynamically typesafe view is generated, and that all subsequent
jaroslav@597: * access to the collection takes place through the view, it is
jaroslav@597: * guaranteed that the collection cannot contain an incorrectly
jaroslav@597: * typed element.
jaroslav@597: *
jaroslav@597: * The generics mechanism in the language provides compile-time
jaroslav@597: * (static) type checking, but it is possible to defeat this mechanism
jaroslav@597: * with unchecked casts. Usually this is not a problem, as the compiler
jaroslav@597: * issues warnings on all such unchecked operations. There are, however,
jaroslav@597: * times when static type checking alone is not sufficient. For example,
jaroslav@597: * suppose a collection is passed to a third-party library and it is
jaroslav@597: * imperative that the library code not corrupt the collection by
jaroslav@597: * inserting an element of the wrong type.
jaroslav@597: *
jaroslav@597: *
Another use of dynamically typesafe views is debugging. Suppose a
jaroslav@597: * program fails with a {@code ClassCastException}, indicating that an
jaroslav@597: * incorrectly typed element was put into a parameterized collection.
jaroslav@597: * Unfortunately, the exception can occur at any time after the erroneous
jaroslav@597: * element is inserted, so it typically provides little or no information
jaroslav@597: * as to the real source of the problem. If the problem is reproducible,
jaroslav@597: * one can quickly determine its source by temporarily modifying the
jaroslav@597: * program to wrap the collection with a dynamically typesafe view.
jaroslav@597: * For example, this declaration:
jaroslav@597: *
{@code
jaroslav@597: * Collection c = new HashSet();
jaroslav@597: * }
jaroslav@597: * may be replaced temporarily by this one:
jaroslav@597: * {@code
jaroslav@597: * Collection c = Collections.checkedCollection(
jaroslav@597: * new HashSet(), String.class);
jaroslav@597: * }
jaroslav@597: * Running the program again will cause it to fail at the point where
jaroslav@597: * an incorrectly typed element is inserted into the collection, clearly
jaroslav@597: * identifying the source of the problem. Once the problem is fixed, the
jaroslav@597: * modified declaration may be reverted back to the original.
jaroslav@597: *
jaroslav@597: * The returned collection does not pass the hashCode and equals
jaroslav@597: * operations through to the backing collection, but relies on
jaroslav@597: * {@code Object}'s {@code equals} and {@code hashCode} methods. This
jaroslav@597: * is necessary to preserve the contracts of these operations in the case
jaroslav@597: * that the backing collection is a set or a list.
jaroslav@597: *
jaroslav@597: *
The returned collection will be serializable if the specified
jaroslav@597: * collection is serializable.
jaroslav@597: *
jaroslav@597: *
Since {@code null} is considered to be a value of any reference
jaroslav@597: * type, the returned collection permits insertion of null elements
jaroslav@597: * whenever the backing collection does.
jaroslav@597: *
jaroslav@597: * @param c the collection for which a dynamically typesafe view is to be
jaroslav@597: * returned
jaroslav@597: * @param type the type of element that {@code c} is permitted to hold
jaroslav@597: * @return a dynamically typesafe view of the specified collection
jaroslav@597: * @since 1.5
jaroslav@597: */
jaroslav@597: public static Collection checkedCollection(Collection c,
jaroslav@597: Class type) {
jaroslav@597: return new CheckedCollection<>(c, type);
jaroslav@597: }
jaroslav@597:
jaroslav@597: @SuppressWarnings("unchecked")
jaroslav@597: static T[] zeroLengthArray(Class type) {
jaroslav@597: return (T[]) Array.newInstance(type, 0);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class CheckedCollection implements Collection, Serializable {
jaroslav@597: private static final long serialVersionUID = 1578914078182001775L;
jaroslav@597:
jaroslav@597: final Collection c;
jaroslav@597: final Class type;
jaroslav@597:
jaroslav@597: void typeCheck(Object o) {
jaroslav@597: if (o != null && !type.isInstance(o))
jaroslav@597: throw new ClassCastException(badElementMsg(o));
jaroslav@597: }
jaroslav@597:
jaroslav@597: private String badElementMsg(Object o) {
jaroslav@597: return "Attempt to insert " + o.getClass() +
jaroslav@597: " element into collection with element type " + type;
jaroslav@597: }
jaroslav@597:
jaroslav@597: CheckedCollection(Collection c, Class type) {
jaroslav@597: if (c==null || type == null)
jaroslav@597: throw new NullPointerException();
jaroslav@597: this.c = c;
jaroslav@597: this.type = type;
jaroslav@597: }
jaroslav@597:
jaroslav@597: public int size() { return c.size(); }
jaroslav@597: public boolean isEmpty() { return c.isEmpty(); }
jaroslav@597: public boolean contains(Object o) { return c.contains(o); }
jaroslav@597: public Object[] toArray() { return c.toArray(); }
jaroslav@597: public T[] toArray(T[] a) { return c.toArray(a); }
jaroslav@597: public String toString() { return c.toString(); }
jaroslav@597: public boolean remove(Object o) { return c.remove(o); }
jaroslav@597: public void clear() { c.clear(); }
jaroslav@597:
jaroslav@597: public boolean containsAll(Collection coll) {
jaroslav@597: return c.containsAll(coll);
jaroslav@597: }
jaroslav@597: public boolean removeAll(Collection coll) {
jaroslav@597: return c.removeAll(coll);
jaroslav@597: }
jaroslav@597: public boolean retainAll(Collection coll) {
jaroslav@597: return c.retainAll(coll);
jaroslav@597: }
jaroslav@597:
jaroslav@597: public Iterator iterator() {
jaroslav@597: final Iterator it = c.iterator();
jaroslav@597: return new Iterator() {
jaroslav@597: public boolean hasNext() { return it.hasNext(); }
jaroslav@597: public E next() { return it.next(); }
jaroslav@597: public void remove() { it.remove(); }};
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean add(E e) {
jaroslav@597: typeCheck(e);
jaroslav@597: return c.add(e);
jaroslav@597: }
jaroslav@597:
jaroslav@597: private E[] zeroLengthElementArray = null; // Lazily initialized
jaroslav@597:
jaroslav@597: private E[] zeroLengthElementArray() {
jaroslav@597: return zeroLengthElementArray != null ? zeroLengthElementArray :
jaroslav@597: (zeroLengthElementArray = zeroLengthArray(type));
jaroslav@597: }
jaroslav@597:
jaroslav@597: @SuppressWarnings("unchecked")
jaroslav@597: Collection checkedCopyOf(Collection coll) {
jaroslav@597: Object[] a = null;
jaroslav@597: try {
jaroslav@597: E[] z = zeroLengthElementArray();
jaroslav@597: a = coll.toArray(z);
jaroslav@597: // Defend against coll violating the toArray contract
jaroslav@597: if (a.getClass() != z.getClass())
jaroslav@597: a = Arrays.copyOf(a, a.length, z.getClass());
jaroslav@597: } catch (ArrayStoreException ignore) {
jaroslav@597: // To get better and consistent diagnostics,
jaroslav@597: // we call typeCheck explicitly on each element.
jaroslav@597: // We call clone() to defend against coll retaining a
jaroslav@597: // reference to the returned array and storing a bad
jaroslav@597: // element into it after it has been type checked.
jaroslav@597: a = coll.toArray().clone();
jaroslav@597: for (Object o : a)
jaroslav@597: typeCheck(o);
jaroslav@597: }
jaroslav@597: // A slight abuse of the type system, but safe here.
jaroslav@597: return (Collection) Arrays.asList(a);
jaroslav@597: }
jaroslav@597:
jaroslav@597: public boolean addAll(Collection coll) {
jaroslav@597: // Doing things this way insulates us from concurrent changes
jaroslav@597: // in the contents of coll and provides all-or-nothing
jaroslav@597: // semantics (which we wouldn't get if we type-checked each
jaroslav@597: // element as we added it)
jaroslav@597: return c.addAll(checkedCopyOf(coll));
jaroslav@597: }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a dynamically typesafe view of the specified set.
jaroslav@597: * Any attempt to insert an element of the wrong type will result in
jaroslav@597: * an immediate {@link ClassCastException}. Assuming a set contains
jaroslav@597: * no incorrectly typed elements prior to the time a dynamically typesafe
jaroslav@597: * view is generated, and that all subsequent access to the set
jaroslav@597: * takes place through the view, it is guaranteed that the
jaroslav@597: * set cannot contain an incorrectly typed element.
jaroslav@597: *
jaroslav@597: * A discussion of the use of dynamically typesafe views may be
jaroslav@597: * found in the documentation for the {@link #checkedCollection
jaroslav@597: * checkedCollection} method.
jaroslav@597: *
jaroslav@597: *
The returned set will be serializable if the specified set is
jaroslav@597: * serializable.
jaroslav@597: *
jaroslav@597: *
Since {@code null} is considered to be a value of any reference
jaroslav@597: * type, the returned set permits insertion of null elements whenever
jaroslav@597: * the backing set does.
jaroslav@597: *
jaroslav@597: * @param s the set for which a dynamically typesafe view is to be
jaroslav@597: * returned
jaroslav@597: * @param type the type of element that {@code s} is permitted to hold
jaroslav@597: * @return a dynamically typesafe view of the specified set
jaroslav@597: * @since 1.5
jaroslav@597: */
jaroslav@597: public static Set checkedSet(Set s, Class type) {
jaroslav@597: return new CheckedSet<>(s, type);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class CheckedSet extends CheckedCollection
jaroslav@597: implements Set, Serializable
jaroslav@597: {
jaroslav@597: private static final long serialVersionUID = 4694047833775013803L;
jaroslav@597:
jaroslav@597: CheckedSet(Set s, Class elementType) { super(s, elementType); }
jaroslav@597:
jaroslav@597: public boolean equals(Object o) { return o == this || c.equals(o); }
jaroslav@597: public int hashCode() { return c.hashCode(); }
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * Returns a dynamically typesafe view of the specified sorted set.
jaroslav@597: * Any attempt to insert an element of the wrong type will result in an
jaroslav@597: * immediate {@link ClassCastException}. Assuming a sorted set
jaroslav@597: * contains no incorrectly typed elements prior to the time a
jaroslav@597: * dynamically typesafe view is generated, and that all subsequent
jaroslav@597: * access to the sorted set takes place through the view, it is
jaroslav@597: * guaranteed that the sorted set cannot contain an incorrectly
jaroslav@597: * typed element.
jaroslav@597: *
jaroslav@597: * A discussion of the use of dynamically typesafe views may be
jaroslav@597: * found in the documentation for the {@link #checkedCollection
jaroslav@597: * checkedCollection} method.
jaroslav@597: *
jaroslav@597: *
The returned sorted set will be serializable if the specified sorted
jaroslav@597: * set is serializable.
jaroslav@597: *
jaroslav@597: *
Since {@code null} is considered to be a value of any reference
jaroslav@597: * type, the returned sorted set permits insertion of null elements
jaroslav@597: * whenever the backing sorted set does.
jaroslav@597: *
jaroslav@597: * @param s the sorted set for which a dynamically typesafe view is to be
jaroslav@597: * returned
jaroslav@597: * @param type the type of element that {@code s} is permitted to hold
jaroslav@597: * @return a dynamically typesafe view of the specified sorted set
jaroslav@597: * @since 1.5
jaroslav@597: */
jaroslav@597: public static SortedSet checkedSortedSet(SortedSet s,
jaroslav@597: Class type) {
jaroslav@597: return new CheckedSortedSet<>(s, type);
jaroslav@597: }
jaroslav@597:
jaroslav@597: /**
jaroslav@597: * @serial include
jaroslav@597: */
jaroslav@597: static class CheckedSortedSet extends CheckedSet
jaroslav@597: implements SortedSet, Serializable
jaroslav@597: {
jaroslav@597: private static final long serialVersionUID = 1599911165492914959L;
jaroslav@597: private final SortedSet