jaroslav@557: /*
jaroslav@557:  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
jaroslav@557:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@557:  *
jaroslav@557:  * This code is free software; you can redistribute it and/or modify it
jaroslav@557:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@557:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@557:  * particular file as subject to the "Classpath" exception as provided
jaroslav@557:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@557:  *
jaroslav@557:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@557:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@557:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@557:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@557:  * accompanied this code).
jaroslav@557:  *
jaroslav@557:  * You should have received a copy of the GNU General Public License version
jaroslav@557:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@557:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@557:  *
jaroslav@557:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@557:  * or visit www.oracle.com if you need additional information or have any
jaroslav@557:  * questions.
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: package java.util;
jaroslav@557: import java.util.Map.Entry;
jaroslav@557: 
jaroslav@557: /**
jaroslav@557:  * This class provides a skeletal implementation of the <tt>Map</tt>
jaroslav@557:  * interface, to minimize the effort required to implement this interface.
jaroslav@557:  *
jaroslav@557:  * <p>To implement an unmodifiable map, the programmer needs only to extend this
jaroslav@557:  * class and provide an implementation for the <tt>entrySet</tt> method, which
jaroslav@557:  * returns a set-view of the map's mappings.  Typically, the returned set
jaroslav@557:  * will, in turn, be implemented atop <tt>AbstractSet</tt>.  This set should
jaroslav@557:  * not support the <tt>add</tt> or <tt>remove</tt> methods, and its iterator
jaroslav@557:  * should not support the <tt>remove</tt> method.
jaroslav@557:  *
jaroslav@557:  * <p>To implement a modifiable map, the programmer must additionally override
jaroslav@557:  * this class's <tt>put</tt> method (which otherwise throws an
jaroslav@557:  * <tt>UnsupportedOperationException</tt>), and the iterator returned by
jaroslav@557:  * <tt>entrySet().iterator()</tt> must additionally implement its
jaroslav@557:  * <tt>remove</tt> method.
jaroslav@557:  *
jaroslav@557:  * <p>The programmer should generally provide a void (no argument) and map
jaroslav@557:  * constructor, as per the recommendation in the <tt>Map</tt> interface
jaroslav@557:  * specification.
jaroslav@557:  *
jaroslav@557:  * <p>The documentation for each non-abstract method in this class describes its
jaroslav@557:  * implementation in detail.  Each of these methods may be overridden if the
jaroslav@557:  * map being implemented admits a more efficient implementation.
jaroslav@557:  *
jaroslav@557:  * <p>This class is a member of the
jaroslav@557:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
jaroslav@557:  * Java Collections Framework</a>.
jaroslav@557:  *
jaroslav@557:  * @param <K> the type of keys maintained by this map
jaroslav@557:  * @param <V> the type of mapped values
jaroslav@557:  *
jaroslav@557:  * @author  Josh Bloch
jaroslav@557:  * @author  Neal Gafter
jaroslav@557:  * @see Map
jaroslav@557:  * @see Collection
jaroslav@557:  * @since 1.2
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: public abstract class AbstractMap<K,V> implements Map<K,V> {
jaroslav@557:     /**
jaroslav@557:      * Sole constructor.  (For invocation by subclass constructors, typically
jaroslav@557:      * implicit.)
jaroslav@557:      */
jaroslav@557:     protected AbstractMap() {
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     // Query Operations
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns <tt>entrySet().size()</tt>.
jaroslav@557:      */
jaroslav@557:     public int size() {
jaroslav@557:         return entrySet().size();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns <tt>size() == 0</tt>.
jaroslav@557:      */
jaroslav@557:     public boolean isEmpty() {
jaroslav@557:         return size() == 0;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over <tt>entrySet()</tt> searching
jaroslav@557:      * for an entry with the specified value.  If such an entry is found,
jaroslav@557:      * <tt>true</tt> is returned.  If the iteration terminates without
jaroslav@557:      * finding such an entry, <tt>false</tt> is returned.  Note that this
jaroslav@557:      * implementation requires linear time in the size of the map.
jaroslav@557:      *
jaroslav@557:      * @throws ClassCastException   {@inheritDoc}
jaroslav@557:      * @throws NullPointerException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public boolean containsValue(Object value) {
jaroslav@557:         Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         if (value==null) {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (e.getValue()==null)
jaroslav@557:                     return true;
jaroslav@557:             }
jaroslav@557:         } else {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (value.equals(e.getValue()))
jaroslav@557:                     return true;
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557:         return false;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over <tt>entrySet()</tt> searching
jaroslav@557:      * for an entry with the specified key.  If such an entry is found,
jaroslav@557:      * <tt>true</tt> is returned.  If the iteration terminates without
jaroslav@557:      * finding such an entry, <tt>false</tt> is returned.  Note that this
jaroslav@557:      * implementation requires linear time in the size of the map; many
jaroslav@557:      * implementations will override this method.
jaroslav@557:      *
jaroslav@557:      * @throws ClassCastException   {@inheritDoc}
jaroslav@557:      * @throws NullPointerException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public boolean containsKey(Object key) {
jaroslav@557:         Iterator<Map.Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         if (key==null) {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (e.getKey()==null)
jaroslav@557:                     return true;
jaroslav@557:             }
jaroslav@557:         } else {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (key.equals(e.getKey()))
jaroslav@557:                     return true;
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557:         return false;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over <tt>entrySet()</tt> searching
jaroslav@557:      * for an entry with the specified key.  If such an entry is found,
jaroslav@557:      * the entry's value is returned.  If the iteration terminates without
jaroslav@557:      * finding such an entry, <tt>null</tt> is returned.  Note that this
jaroslav@557:      * implementation requires linear time in the size of the map; many
jaroslav@557:      * implementations will override this method.
jaroslav@557:      *
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public V get(Object key) {
jaroslav@557:         Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         if (key==null) {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (e.getKey()==null)
jaroslav@557:                     return e.getValue();
jaroslav@557:             }
jaroslav@557:         } else {
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (key.equals(e.getKey()))
jaroslav@557:                     return e.getValue();
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557:         return null;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Modification Operations
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation always throws an
jaroslav@557:      * <tt>UnsupportedOperationException</tt>.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      * @throws IllegalArgumentException      {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public V put(K key, V value) {
jaroslav@557:         throw new UnsupportedOperationException();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over <tt>entrySet()</tt> searching for an
jaroslav@557:      * entry with the specified key.  If such an entry is found, its value is
jaroslav@557:      * obtained with its <tt>getValue</tt> operation, the entry is removed
jaroslav@557:      * from the collection (and the backing map) with the iterator's
jaroslav@557:      * <tt>remove</tt> operation, and the saved value is returned.  If the
jaroslav@557:      * iteration terminates without finding such an entry, <tt>null</tt> is
jaroslav@557:      * returned.  Note that this implementation requires linear time in the
jaroslav@557:      * size of the map; many implementations will override this method.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt>
jaroslav@557:      * iterator does not support the <tt>remove</tt> method and this map
jaroslav@557:      * contains a mapping for the specified key.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public V remove(Object key) {
jaroslav@557:         Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         Entry<K,V> correctEntry = null;
jaroslav@557:         if (key==null) {
jaroslav@557:             while (correctEntry==null && i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (e.getKey()==null)
jaroslav@557:                     correctEntry = e;
jaroslav@557:             }
jaroslav@557:         } else {
jaroslav@557:             while (correctEntry==null && i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 if (key.equals(e.getKey()))
jaroslav@557:                     correctEntry = e;
jaroslav@557:             }
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         V oldValue = null;
jaroslav@557:         if (correctEntry !=null) {
jaroslav@557:             oldValue = correctEntry.getValue();
jaroslav@557:             i.remove();
jaroslav@557:         }
jaroslav@557:         return oldValue;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Bulk Operations
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over the specified map's
jaroslav@557:      * <tt>entrySet()</tt> collection, and calls this map's <tt>put</tt>
jaroslav@557:      * operation once for each entry returned by the iteration.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * <tt>UnsupportedOperationException</tt> if this map does not support
jaroslav@557:      * the <tt>put</tt> operation and the specified map is nonempty.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      * @throws ClassCastException            {@inheritDoc}
jaroslav@557:      * @throws NullPointerException          {@inheritDoc}
jaroslav@557:      * @throws IllegalArgumentException      {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public void putAll(Map<? extends K, ? extends V> m) {
jaroslav@557:         for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
jaroslav@557:             put(e.getKey(), e.getValue());
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation calls <tt>entrySet().clear()</tt>.
jaroslav@557:      *
jaroslav@557:      * <p>Note that this implementation throws an
jaroslav@557:      * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt>
jaroslav@557:      * does not support the <tt>clear</tt> operation.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException {@inheritDoc}
jaroslav@557:      */
jaroslav@557:     public void clear() {
jaroslav@557:         entrySet().clear();
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Views
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Each of these fields are initialized to contain an instance of the
jaroslav@557:      * appropriate view the first time this view is requested.  The views are
jaroslav@557:      * stateless, so there's no reason to create more than one of each.
jaroslav@557:      */
jaroslav@557:     transient volatile Set<K>        keySet = null;
jaroslav@557:     transient volatile Collection<V> values = null;
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns a set that subclasses {@link AbstractSet}.
jaroslav@557:      * The subclass's iterator method returns a "wrapper object" over this
jaroslav@557:      * map's <tt>entrySet()</tt> iterator.  The <tt>size</tt> method
jaroslav@557:      * delegates to this map's <tt>size</tt> method and the
jaroslav@557:      * <tt>contains</tt> method delegates to this map's
jaroslav@557:      * <tt>containsKey</tt> method.
jaroslav@557:      *
jaroslav@557:      * <p>The set is created the first time this method is called,
jaroslav@557:      * and returned in response to all subsequent calls.  No synchronization
jaroslav@557:      * is performed, so there is a slight chance that multiple calls to this
jaroslav@557:      * method will not all return the same set.
jaroslav@557:      */
jaroslav@557:     public Set<K> keySet() {
jaroslav@557:         if (keySet == null) {
jaroslav@557:             keySet = new AbstractSet<K>() {
jaroslav@557:                 public Iterator<K> iterator() {
jaroslav@557:                     return new Iterator<K>() {
jaroslav@557:                         private Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557: 
jaroslav@557:                         public boolean hasNext() {
jaroslav@557:                             return i.hasNext();
jaroslav@557:                         }
jaroslav@557: 
jaroslav@557:                         public K next() {
jaroslav@557:                             return i.next().getKey();
jaroslav@557:                         }
jaroslav@557: 
jaroslav@557:                         public void remove() {
jaroslav@557:                             i.remove();
jaroslav@557:                         }
jaroslav@557:                     };
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public int size() {
jaroslav@557:                     return AbstractMap.this.size();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public boolean isEmpty() {
jaroslav@557:                     return AbstractMap.this.isEmpty();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public void clear() {
jaroslav@557:                     AbstractMap.this.clear();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public boolean contains(Object k) {
jaroslav@557:                     return AbstractMap.this.containsKey(k);
jaroslav@557:                 }
jaroslav@557:             };
jaroslav@557:         }
jaroslav@557:         return keySet;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * {@inheritDoc}
jaroslav@557:      *
jaroslav@557:      * <p>This implementation returns a collection that subclasses {@link
jaroslav@557:      * AbstractCollection}.  The subclass's iterator method returns a
jaroslav@557:      * "wrapper object" over this map's <tt>entrySet()</tt> iterator.
jaroslav@557:      * The <tt>size</tt> method delegates to this map's <tt>size</tt>
jaroslav@557:      * method and the <tt>contains</tt> method delegates to this map's
jaroslav@557:      * <tt>containsValue</tt> method.
jaroslav@557:      *
jaroslav@557:      * <p>The collection is created the first time this method is called, and
jaroslav@557:      * returned in response to all subsequent calls.  No synchronization is
jaroslav@557:      * performed, so there is a slight chance that multiple calls to this
jaroslav@557:      * method will not all return the same collection.
jaroslav@557:      */
jaroslav@557:     public Collection<V> values() {
jaroslav@557:         if (values == null) {
jaroslav@557:             values = new AbstractCollection<V>() {
jaroslav@557:                 public Iterator<V> iterator() {
jaroslav@557:                     return new Iterator<V>() {
jaroslav@557:                         private Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557: 
jaroslav@557:                         public boolean hasNext() {
jaroslav@557:                             return i.hasNext();
jaroslav@557:                         }
jaroslav@557: 
jaroslav@557:                         public V next() {
jaroslav@557:                             return i.next().getValue();
jaroslav@557:                         }
jaroslav@557: 
jaroslav@557:                         public void remove() {
jaroslav@557:                             i.remove();
jaroslav@557:                         }
jaroslav@557:                     };
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public int size() {
jaroslav@557:                     return AbstractMap.this.size();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public boolean isEmpty() {
jaroslav@557:                     return AbstractMap.this.isEmpty();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public void clear() {
jaroslav@557:                     AbstractMap.this.clear();
jaroslav@557:                 }
jaroslav@557: 
jaroslav@557:                 public boolean contains(Object v) {
jaroslav@557:                     return AbstractMap.this.containsValue(v);
jaroslav@557:                 }
jaroslav@557:             };
jaroslav@557:         }
jaroslav@557:         return values;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     public abstract Set<Entry<K,V>> entrySet();
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     // Comparison and hashing
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Compares the specified object with this map for equality.  Returns
jaroslav@557:      * <tt>true</tt> if the given object is also a map and the two maps
jaroslav@557:      * represent the same mappings.  More formally, two maps <tt>m1</tt> and
jaroslav@557:      * <tt>m2</tt> represent the same mappings if
jaroslav@557:      * <tt>m1.entrySet().equals(m2.entrySet())</tt>.  This ensures that the
jaroslav@557:      * <tt>equals</tt> method works properly across different implementations
jaroslav@557:      * of the <tt>Map</tt> interface.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation first checks if the specified object is this map;
jaroslav@557:      * if so it returns <tt>true</tt>.  Then, it checks if the specified
jaroslav@557:      * object is a map whose size is identical to the size of this map; if
jaroslav@557:      * not, it returns <tt>false</tt>.  If so, it iterates over this map's
jaroslav@557:      * <tt>entrySet</tt> collection, and checks that the specified map
jaroslav@557:      * contains each mapping that this map contains.  If the specified map
jaroslav@557:      * fails to contain such a mapping, <tt>false</tt> is returned.  If the
jaroslav@557:      * iteration completes, <tt>true</tt> is returned.
jaroslav@557:      *
jaroslav@557:      * @param o object to be compared for equality with this map
jaroslav@557:      * @return <tt>true</tt> if the specified object is equal to this map
jaroslav@557:      */
jaroslav@557:     public boolean equals(Object o) {
jaroslav@557:         if (o == this)
jaroslav@557:             return true;
jaroslav@557: 
jaroslav@557:         if (!(o instanceof Map))
jaroslav@557:             return false;
jaroslav@557:         Map<K,V> m = (Map<K,V>) o;
jaroslav@557:         if (m.size() != size())
jaroslav@557:             return false;
jaroslav@557: 
jaroslav@557:         try {
jaroslav@557:             Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:             while (i.hasNext()) {
jaroslav@557:                 Entry<K,V> e = i.next();
jaroslav@557:                 K key = e.getKey();
jaroslav@557:                 V value = e.getValue();
jaroslav@557:                 if (value == null) {
jaroslav@557:                     if (!(m.get(key)==null && m.containsKey(key)))
jaroslav@557:                         return false;
jaroslav@557:                 } else {
jaroslav@557:                     if (!value.equals(m.get(key)))
jaroslav@557:                         return false;
jaroslav@557:                 }
jaroslav@557:             }
jaroslav@557:         } catch (ClassCastException unused) {
jaroslav@557:             return false;
jaroslav@557:         } catch (NullPointerException unused) {
jaroslav@557:             return false;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         return true;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns the hash code value for this map.  The hash code of a map is
jaroslav@557:      * defined to be the sum of the hash codes of each entry in the map's
jaroslav@557:      * <tt>entrySet()</tt> view.  This ensures that <tt>m1.equals(m2)</tt>
jaroslav@557:      * implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps
jaroslav@557:      * <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of
jaroslav@557:      * {@link Object#hashCode}.
jaroslav@557:      *
jaroslav@557:      * <p>This implementation iterates over <tt>entrySet()</tt>, calling
jaroslav@557:      * {@link Map.Entry#hashCode hashCode()} on each element (entry) in the
jaroslav@557:      * set, and adding up the results.
jaroslav@557:      *
jaroslav@557:      * @return the hash code value for this map
jaroslav@557:      * @see Map.Entry#hashCode()
jaroslav@557:      * @see Object#equals(Object)
jaroslav@557:      * @see Set#equals(Object)
jaroslav@557:      */
jaroslav@557:     public int hashCode() {
jaroslav@557:         int h = 0;
jaroslav@557:         Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         while (i.hasNext())
jaroslav@557:             h += i.next().hashCode();
jaroslav@557:         return h;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns a string representation of this map.  The string representation
jaroslav@557:      * consists of a list of key-value mappings in the order returned by the
jaroslav@557:      * map's <tt>entrySet</tt> view's iterator, enclosed in braces
jaroslav@557:      * (<tt>"{}"</tt>).  Adjacent mappings are separated by the characters
jaroslav@557:      * <tt>", "</tt> (comma and space).  Each key-value mapping is rendered as
jaroslav@557:      * the key followed by an equals sign (<tt>"="</tt>) followed by the
jaroslav@557:      * associated value.  Keys and values are converted to strings as by
jaroslav@557:      * {@link String#valueOf(Object)}.
jaroslav@557:      *
jaroslav@557:      * @return a string representation of this map
jaroslav@557:      */
jaroslav@557:     public String toString() {
jaroslav@557:         Iterator<Entry<K,V>> i = entrySet().iterator();
jaroslav@557:         if (! i.hasNext())
jaroslav@557:             return "{}";
jaroslav@557: 
jaroslav@557:         StringBuilder sb = new StringBuilder();
jaroslav@557:         sb.append('{');
jaroslav@557:         for (;;) {
jaroslav@557:             Entry<K,V> e = i.next();
jaroslav@557:             K key = e.getKey();
jaroslav@557:             V value = e.getValue();
jaroslav@557:             sb.append(key   == this ? "(this Map)" : key);
jaroslav@557:             sb.append('=');
jaroslav@557:             sb.append(value == this ? "(this Map)" : value);
jaroslav@557:             if (! i.hasNext())
jaroslav@557:                 return sb.append('}').toString();
jaroslav@557:             sb.append(',').append(' ');
jaroslav@557:         }
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys
jaroslav@557:      * and values themselves are not cloned.
jaroslav@557:      *
jaroslav@557:      * @return a shallow copy of this map
jaroslav@557:      */
jaroslav@557:     protected Object clone() throws CloneNotSupportedException {
jaroslav@557:         AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone();
jaroslav@557:         result.keySet = null;
jaroslav@557:         result.values = null;
jaroslav@557:         return result;
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Utility method for SimpleEntry and SimpleImmutableEntry.
jaroslav@557:      * Test for equality, checking for nulls.
jaroslav@557:      */
jaroslav@557:     private static boolean eq(Object o1, Object o2) {
jaroslav@557:         return o1 == null ? o2 == null : o1.equals(o2);
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     // Implementation Note: SimpleEntry and SimpleImmutableEntry
jaroslav@557:     // are distinct unrelated classes, even though they share
jaroslav@557:     // some code. Since you can't add or subtract final-ness
jaroslav@557:     // of a field in a subclass, they can't share representations,
jaroslav@557:     // and the amount of duplicated code is too small to warrant
jaroslav@557:     // exposing a common abstract class.
jaroslav@557: 
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * An Entry maintaining a key and a value.  The value may be
jaroslav@557:      * changed using the <tt>setValue</tt> method.  This class
jaroslav@557:      * facilitates the process of building custom map
jaroslav@557:      * implementations. For example, it may be convenient to return
jaroslav@557:      * arrays of <tt>SimpleEntry</tt> instances in method
jaroslav@557:      * <tt>Map.entrySet().toArray</tt>.
jaroslav@557:      *
jaroslav@557:      * @since 1.6
jaroslav@557:      */
jaroslav@557:     public static class SimpleEntry<K,V>
jaroslav@557:         implements Entry<K,V>, java.io.Serializable
jaroslav@557:     {
jaroslav@557:         private static final long serialVersionUID = -8499721149061103585L;
jaroslav@557: 
jaroslav@557:         private final K key;
jaroslav@557:         private V value;
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Creates an entry representing a mapping from the specified
jaroslav@557:          * key to the specified value.
jaroslav@557:          *
jaroslav@557:          * @param key the key represented by this entry
jaroslav@557:          * @param value the value represented by this entry
jaroslav@557:          */
jaroslav@557:         public SimpleEntry(K key, V value) {
jaroslav@557:             this.key   = key;
jaroslav@557:             this.value = value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Creates an entry representing the same mapping as the
jaroslav@557:          * specified entry.
jaroslav@557:          *
jaroslav@557:          * @param entry the entry to copy
jaroslav@557:          */
jaroslav@557:         public SimpleEntry(Entry<? extends K, ? extends V> entry) {
jaroslav@557:             this.key   = entry.getKey();
jaroslav@557:             this.value = entry.getValue();
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the key corresponding to this entry.
jaroslav@557:          *
jaroslav@557:          * @return the key corresponding to this entry
jaroslav@557:          */
jaroslav@557:         public K getKey() {
jaroslav@557:             return key;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the value corresponding to this entry.
jaroslav@557:          *
jaroslav@557:          * @return the value corresponding to this entry
jaroslav@557:          */
jaroslav@557:         public V getValue() {
jaroslav@557:             return value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Replaces the value corresponding to this entry with the specified
jaroslav@557:          * value.
jaroslav@557:          *
jaroslav@557:          * @param value new value to be stored in this entry
jaroslav@557:          * @return the old value corresponding to the entry
jaroslav@557:          */
jaroslav@557:         public V setValue(V value) {
jaroslav@557:             V oldValue = this.value;
jaroslav@557:             this.value = value;
jaroslav@557:             return oldValue;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Compares the specified object with this entry for equality.
jaroslav@557:          * Returns {@code true} if the given object is also a map entry and
jaroslav@557:          * the two entries represent the same mapping.  More formally, two
jaroslav@557:          * entries {@code e1} and {@code e2} represent the same mapping
jaroslav@557:          * if<pre>
jaroslav@557:          *   (e1.getKey()==null ?
jaroslav@557:          *    e2.getKey()==null :
jaroslav@557:          *    e1.getKey().equals(e2.getKey()))
jaroslav@557:          *   &amp;&amp;
jaroslav@557:          *   (e1.getValue()==null ?
jaroslav@557:          *    e2.getValue()==null :
jaroslav@557:          *    e1.getValue().equals(e2.getValue()))</pre>
jaroslav@557:          * This ensures that the {@code equals} method works properly across
jaroslav@557:          * different implementations of the {@code Map.Entry} interface.
jaroslav@557:          *
jaroslav@557:          * @param o object to be compared for equality with this map entry
jaroslav@557:          * @return {@code true} if the specified object is equal to this map
jaroslav@557:          *         entry
jaroslav@557:          * @see    #hashCode
jaroslav@557:          */
jaroslav@557:         public boolean equals(Object o) {
jaroslav@557:             if (!(o instanceof Map.Entry))
jaroslav@557:                 return false;
jaroslav@557:             Map.Entry e = (Map.Entry)o;
jaroslav@557:             return eq(key, e.getKey()) && eq(value, e.getValue());
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the hash code value for this map entry.  The hash code
jaroslav@557:          * of a map entry {@code e} is defined to be: <pre>
jaroslav@557:          *   (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
jaroslav@557:          *   (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
jaroslav@557:          * This ensures that {@code e1.equals(e2)} implies that
jaroslav@557:          * {@code e1.hashCode()==e2.hashCode()} for any two Entries
jaroslav@557:          * {@code e1} and {@code e2}, as required by the general
jaroslav@557:          * contract of {@link Object#hashCode}.
jaroslav@557:          *
jaroslav@557:          * @return the hash code value for this map entry
jaroslav@557:          * @see    #equals
jaroslav@557:          */
jaroslav@557:         public int hashCode() {
jaroslav@557:             return (key   == null ? 0 :   key.hashCode()) ^
jaroslav@557:                    (value == null ? 0 : value.hashCode());
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns a String representation of this map entry.  This
jaroslav@557:          * implementation returns the string representation of this
jaroslav@557:          * entry's key followed by the equals character ("<tt>=</tt>")
jaroslav@557:          * followed by the string representation of this entry's value.
jaroslav@557:          *
jaroslav@557:          * @return a String representation of this map entry
jaroslav@557:          */
jaroslav@557:         public String toString() {
jaroslav@557:             return key + "=" + value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:     }
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * An Entry maintaining an immutable key and value.  This class
jaroslav@557:      * does not support method <tt>setValue</tt>.  This class may be
jaroslav@557:      * convenient in methods that return thread-safe snapshots of
jaroslav@557:      * key-value mappings.
jaroslav@557:      *
jaroslav@557:      * @since 1.6
jaroslav@557:      */
jaroslav@557:     public static class SimpleImmutableEntry<K,V>
jaroslav@557:         implements Entry<K,V>, java.io.Serializable
jaroslav@557:     {
jaroslav@557:         private static final long serialVersionUID = 7138329143949025153L;
jaroslav@557: 
jaroslav@557:         private final K key;
jaroslav@557:         private final V value;
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Creates an entry representing a mapping from the specified
jaroslav@557:          * key to the specified value.
jaroslav@557:          *
jaroslav@557:          * @param key the key represented by this entry
jaroslav@557:          * @param value the value represented by this entry
jaroslav@557:          */
jaroslav@557:         public SimpleImmutableEntry(K key, V value) {
jaroslav@557:             this.key   = key;
jaroslav@557:             this.value = value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Creates an entry representing the same mapping as the
jaroslav@557:          * specified entry.
jaroslav@557:          *
jaroslav@557:          * @param entry the entry to copy
jaroslav@557:          */
jaroslav@557:         public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) {
jaroslav@557:             this.key   = entry.getKey();
jaroslav@557:             this.value = entry.getValue();
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the key corresponding to this entry.
jaroslav@557:          *
jaroslav@557:          * @return the key corresponding to this entry
jaroslav@557:          */
jaroslav@557:         public K getKey() {
jaroslav@557:             return key;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the value corresponding to this entry.
jaroslav@557:          *
jaroslav@557:          * @return the value corresponding to this entry
jaroslav@557:          */
jaroslav@557:         public V getValue() {
jaroslav@557:             return value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Replaces the value corresponding to this entry with the specified
jaroslav@557:          * value (optional operation).  This implementation simply throws
jaroslav@557:          * <tt>UnsupportedOperationException</tt>, as this class implements
jaroslav@557:          * an <i>immutable</i> map entry.
jaroslav@557:          *
jaroslav@557:          * @param value new value to be stored in this entry
jaroslav@557:          * @return (Does not return)
jaroslav@557:          * @throws UnsupportedOperationException always
jaroslav@557:          */
jaroslav@557:         public V setValue(V value) {
jaroslav@557:             throw new UnsupportedOperationException();
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Compares the specified object with this entry for equality.
jaroslav@557:          * Returns {@code true} if the given object is also a map entry and
jaroslav@557:          * the two entries represent the same mapping.  More formally, two
jaroslav@557:          * entries {@code e1} and {@code e2} represent the same mapping
jaroslav@557:          * if<pre>
jaroslav@557:          *   (e1.getKey()==null ?
jaroslav@557:          *    e2.getKey()==null :
jaroslav@557:          *    e1.getKey().equals(e2.getKey()))
jaroslav@557:          *   &amp;&amp;
jaroslav@557:          *   (e1.getValue()==null ?
jaroslav@557:          *    e2.getValue()==null :
jaroslav@557:          *    e1.getValue().equals(e2.getValue()))</pre>
jaroslav@557:          * This ensures that the {@code equals} method works properly across
jaroslav@557:          * different implementations of the {@code Map.Entry} interface.
jaroslav@557:          *
jaroslav@557:          * @param o object to be compared for equality with this map entry
jaroslav@557:          * @return {@code true} if the specified object is equal to this map
jaroslav@557:          *         entry
jaroslav@557:          * @see    #hashCode
jaroslav@557:          */
jaroslav@557:         public boolean equals(Object o) {
jaroslav@557:             if (!(o instanceof Map.Entry))
jaroslav@557:                 return false;
jaroslav@557:             Map.Entry e = (Map.Entry)o;
jaroslav@557:             return eq(key, e.getKey()) && eq(value, e.getValue());
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns the hash code value for this map entry.  The hash code
jaroslav@557:          * of a map entry {@code e} is defined to be: <pre>
jaroslav@557:          *   (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
jaroslav@557:          *   (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
jaroslav@557:          * This ensures that {@code e1.equals(e2)} implies that
jaroslav@557:          * {@code e1.hashCode()==e2.hashCode()} for any two Entries
jaroslav@557:          * {@code e1} and {@code e2}, as required by the general
jaroslav@557:          * contract of {@link Object#hashCode}.
jaroslav@557:          *
jaroslav@557:          * @return the hash code value for this map entry
jaroslav@557:          * @see    #equals
jaroslav@557:          */
jaroslav@557:         public int hashCode() {
jaroslav@557:             return (key   == null ? 0 :   key.hashCode()) ^
jaroslav@557:                    (value == null ? 0 : value.hashCode());
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:         /**
jaroslav@557:          * Returns a String representation of this map entry.  This
jaroslav@557:          * implementation returns the string representation of this
jaroslav@557:          * entry's key followed by the equals character ("<tt>=</tt>")
jaroslav@557:          * followed by the string representation of this entry's value.
jaroslav@557:          *
jaroslav@557:          * @return a String representation of this map entry
jaroslav@557:          */
jaroslav@557:         public String toString() {
jaroslav@557:             return key + "=" + value;
jaroslav@557:         }
jaroslav@557: 
jaroslav@557:     }
jaroslav@557: 
jaroslav@557: }