- * String buffers are safe for use by multiple threads. The methods - * are synchronized where necessary so that all the operations on any - * particular instance behave as if they occur in some serial order - * that is consistent with the order of the method calls made by each of - * the individual threads involved. - *
- * The principal operations on a StringBuffer are the
- * append and insert methods, which are
- * overloaded so as to accept data of any type. Each effectively
- * converts a given datum to a string and then appends or inserts the
- * characters of that string to the string buffer. The
- * append method always adds these characters at the end
- * of the buffer; the insert method adds the characters at
- * a specified point.
- *
- * For example, if z refers to a string buffer object
- * whose current contents are "start", then
- * the method call z.append("le") would cause the string
- * buffer to contain "startle", whereas
- * z.insert(4, "le") would alter the string buffer to
- * contain "starlet".
- *
- * In general, if sb refers to an instance of a StringBuffer,
- * then sb.append(x) has the same effect as
- * sb.insert(sb.length(), x).
- *
- * Whenever an operation occurs involving a source sequence (such as - * appending or inserting from a source sequence) this class synchronizes - * only on the string buffer performing the operation, not on the source. - *
- * Every string buffer has a capacity. As long as the length of the
- * character sequence contained in the string buffer does not exceed
- * the capacity, it is not necessary to allocate a new internal
- * buffer array. If the internal buffer overflows, it is
- * automatically made larger.
- *
- * As of release JDK 5, this class has been supplemented with an equivalent
- * class designed for use by a single thread, {@link StringBuilder}. The
- * StringBuilder class should generally be used in preference to
- * this one, as it supports all of the same operations but it is faster, as
- * it performs no synchronization.
- *
- * @author Arthur van Hoff
- * @see java.lang.StringBuilder
- * @see java.lang.String
- * @since JDK1.0
- */
- public final class StringBuffer
- extends AbstractStringBuilder
- implements java.io.Serializable, CharSequence
-{
-
- /** use serialVersionUID from JDK 1.0.2 for interoperability */
- static final long serialVersionUID = 3388685877147921107L;
-
- /**
- * Constructs a string buffer with no characters in it and an
- * initial capacity of 16 characters.
- */
- public StringBuffer() {
- super(16);
- }
-
- /**
- * Constructs a string buffer with no characters in it and
- * the specified initial capacity.
- *
- * @param capacity the initial capacity.
- * @exception NegativeArraySizeException if the capacity
- * argument is less than 0.
- */
- public StringBuffer(int capacity) {
- super(capacity);
- }
-
- /**
- * Constructs a string buffer initialized to the contents of the
- * specified string. The initial capacity of the string buffer is
- * 16 plus the length of the string argument.
- *
- * @param str the initial contents of the buffer.
- * @exception NullPointerException if str is null
- */
- public StringBuffer(String str) {
- super(str.length() + 16);
- append(str);
- }
-
- /**
- * Constructs a string buffer that contains the same characters
- * as the specified CharSequence. The initial capacity of
- * the string buffer is 16 plus the length of the
- * CharSequence argument.
- *
- * If the length of the specified CharSequence is
- * less than or equal to zero, then an empty buffer of capacity
- * 16 is returned.
- *
- * @param seq the sequence to copy.
- * @exception NullPointerException if seq is null
- * @since 1.5
- */
- public StringBuffer(CharSequence seq) {
- this(seq.length() + 16);
- append(seq);
- }
-
- public synchronized int length() {
- return count;
- }
-
- public synchronized int capacity() {
- return value.length;
- }
-
-
- public synchronized void ensureCapacity(int minimumCapacity) {
- if (minimumCapacity > value.length) {
- expandCapacity(minimumCapacity);
- }
- }
-
- /**
- * @since 1.5
- */
- public synchronized void trimToSize() {
- super.trimToSize();
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @see #length()
- */
- public synchronized void setLength(int newLength) {
- super.setLength(newLength);
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @see #length()
- */
- public synchronized char charAt(int index) {
- if ((index < 0) || (index >= count))
- throw new StringIndexOutOfBoundsException(index);
- return value[index];
- }
-
- /**
- * @since 1.5
- */
- public synchronized int codePointAt(int index) {
- return super.codePointAt(index);
- }
-
- /**
- * @since 1.5
- */
- public synchronized int codePointBefore(int index) {
- return super.codePointBefore(index);
- }
-
- /**
- * @since 1.5
- */
- public synchronized int codePointCount(int beginIndex, int endIndex) {
- return super.codePointCount(beginIndex, endIndex);
- }
-
- /**
- * @since 1.5
- */
- public synchronized int offsetByCodePoints(int index, int codePointOffset) {
- return super.offsetByCodePoints(index, codePointOffset);
- }
-
- /**
- * @throws NullPointerException {@inheritDoc}
- * @throws IndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized void getChars(int srcBegin, int srcEnd, char[] dst,
- int dstBegin)
- {
- super.getChars(srcBegin, srcEnd, dst, dstBegin);
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @see #length()
- */
- public synchronized void setCharAt(int index, char ch) {
- if ((index < 0) || (index >= count))
- throw new StringIndexOutOfBoundsException(index);
- value[index] = ch;
- }
-
- public synchronized StringBuffer append(Object obj) {
- super.append(String.valueOf(obj));
- return this;
- }
-
- public synchronized StringBuffer append(String str) {
- super.append(str);
- return this;
- }
-
- /**
- * Appends the specified StringBuffer to this sequence.
- *
- * The characters of the StringBuffer argument are appended, - * in order, to the contents of this StringBuffer, increasing the - * length of this StringBuffer by the length of the argument. - * If sb is null, then the four characters - * "null" are appended to this StringBuffer. - *
- * Let n be the length of the old character sequence, the one
- * contained in the StringBuffer just prior to execution of the
- * append method. Then the character at index k in
- * the new character sequence is equal to the character at index k
- * in the old character sequence, if k is less than n;
- * otherwise, it is equal to the character at index k-n in the
- * argument sb.
- *
- * This method synchronizes on this (the destination)
- * object but does not synchronize on the source (sb).
- *
- * @param sb the StringBuffer to append.
- * @return a reference to this object.
- * @since 1.4
- */
- public synchronized StringBuffer append(StringBuffer sb) {
- super.append(sb);
- return this;
- }
-
-
- /**
- * Appends the specified CharSequence to this
- * sequence.
- *
- * The characters of the CharSequence argument are appended,
- * in order, increasing the length of this sequence by the length of the
- * argument.
- *
- *
The result of this method is exactly the same as if it were an - * invocation of this.append(s, 0, s.length()); - * - *
This method synchronizes on this (the destination)
- * object but does not synchronize on the source (s).
- *
- *
If s is null, then the four characters
- * "null" are appended.
- *
- * @param s the CharSequence to append.
- * @return a reference to this object.
- * @since 1.5
- */
- public StringBuffer append(CharSequence s) {
- // Note, synchronization achieved via other invocations
- if (s == null)
- s = "null";
- if (s instanceof String)
- return this.append((String)s);
- if (s instanceof StringBuffer)
- return this.append((StringBuffer)s);
- return this.append(s, 0, s.length());
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @since 1.5
- */
- public synchronized StringBuffer append(CharSequence s, int start, int end)
- {
- super.append(s, start, end);
- return this;
- }
-
- public synchronized StringBuffer append(char[] str) {
- super.append(str);
- return this;
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized StringBuffer append(char[] str, int offset, int len) {
- super.append(str, offset, len);
- return this;
- }
-
- public synchronized StringBuffer append(boolean b) {
- super.append(b);
- return this;
- }
-
- public synchronized StringBuffer append(char c) {
- super.append(c);
- return this;
- }
-
- public synchronized StringBuffer append(int i) {
- super.append(i);
- return this;
- }
-
- /**
- * @since 1.5
- */
- public synchronized StringBuffer appendCodePoint(int codePoint) {
- super.appendCodePoint(codePoint);
- return this;
- }
-
- public synchronized StringBuffer append(long lng) {
- super.append(lng);
- return this;
- }
-
- public synchronized StringBuffer append(float f) {
- super.append(f);
- return this;
- }
-
- public synchronized StringBuffer append(double d) {
- super.append(d);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized StringBuffer delete(int start, int end) {
- super.delete(start, end);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized StringBuffer deleteCharAt(int index) {
- super.deleteCharAt(index);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized StringBuffer replace(int start, int end, String str) {
- super.replace(start, end, str);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized String substring(int start) {
- return substring(start, count);
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @since 1.4
- */
- public synchronized CharSequence subSequence(int start, int end) {
- return super.substring(start, end);
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized String substring(int start, int end) {
- return super.substring(start, end);
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- * @since 1.2
- */
- public synchronized StringBuffer insert(int index, char[] str, int offset,
- int len)
- {
- super.insert(index, str, offset, len);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized StringBuffer insert(int offset, Object obj) {
- super.insert(offset, String.valueOf(obj));
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized StringBuffer insert(int offset, String str) {
- super.insert(offset, str);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized StringBuffer insert(int offset, char[] str) {
- super.insert(offset, str);
- return this;
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @since 1.5
- */
- public StringBuffer insert(int dstOffset, CharSequence s) {
- // Note, synchronization achieved via other invocations
- if (s == null)
- s = "null";
- if (s instanceof String)
- return this.insert(dstOffset, (String)s);
- return this.insert(dstOffset, s, 0, s.length());
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- * @since 1.5
- */
- public synchronized StringBuffer insert(int dstOffset, CharSequence s,
- int start, int end)
- {
- super.insert(dstOffset, s, start, end);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public StringBuffer insert(int offset, boolean b) {
- return insert(offset, String.valueOf(b));
- }
-
- /**
- * @throws IndexOutOfBoundsException {@inheritDoc}
- */
- public synchronized StringBuffer insert(int offset, char c) {
- super.insert(offset, c);
- return this;
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public StringBuffer insert(int offset, int i) {
- return insert(offset, String.valueOf(i));
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public StringBuffer insert(int offset, long l) {
- return insert(offset, String.valueOf(l));
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public StringBuffer insert(int offset, float f) {
- return insert(offset, String.valueOf(f));
- }
-
- /**
- * @throws StringIndexOutOfBoundsException {@inheritDoc}
- */
- public StringBuffer insert(int offset, double d) {
- return insert(offset, String.valueOf(d));
- }
-
- /**
- * @throws NullPointerException {@inheritDoc}
- * @since 1.4
- */
- public int indexOf(String str) {
- return indexOf(str, 0);
- }
-
- /**
- * @throws NullPointerException {@inheritDoc}
- * @since 1.4
- */
- public synchronized int indexOf(String str, int fromIndex) {
- return super.indexOf(str, fromIndex);
- }
-
- /**
- * @throws NullPointerException {@inheritDoc}
- * @since 1.4
- */
- public int lastIndexOf(String str) {
- // Note, synchronization achieved via other invocations
- return lastIndexOf(str, count);
- }
-
- /**
- * @throws NullPointerException {@inheritDoc}
- * @since 1.4
- */
- public synchronized int lastIndexOf(String str, int fromIndex) {
- return String.lastIndexOf(value, 0, count,
- str.toCharArray(), 0, str.length(), fromIndex);
- }
-
- /**
- * @since JDK1.0.2
- */
- public synchronized StringBuffer reverse() {
- super.reverse();
- return this;
- }
-
- public synchronized String toString() {
- return new String(value, 0, count);
- }
-
-// /**
-// * Serializable fields for StringBuffer.
-// *
-// * @serialField value char[]
-// * The backing character array of this StringBuffer.
-// * @serialField count int
-// * The number of characters in this StringBuffer.
-// * @serialField shared boolean
-// * A flag indicating whether the backing array is shared.
-// * The value is ignored upon deserialization.
-// */
-// private static final java.io.ObjectStreamField[] serialPersistentFields =
-// {
-// new java.io.ObjectStreamField("value", char[].class),
-// new java.io.ObjectStreamField("count", Integer.TYPE),
-// new java.io.ObjectStreamField("shared", Boolean.TYPE),
-// };
-//
-// /**
-// * readObject is called to restore the state of the StringBuffer from
-// * a stream.
-// */
-// private synchronized void writeObject(java.io.ObjectOutputStream s)
-// throws java.io.IOException {
-// java.io.ObjectOutputStream.PutField fields = s.putFields();
-// fields.put("value", value);
-// fields.put("count", count);
-// fields.put("shared", false);
-// s.writeFields();
-// }
-//
-// /**
-// * readObject is called to restore the state of the StringBuffer from
-// * a stream.
-// */
-// private void readObject(java.io.ObjectInputStream s)
-// throws java.io.IOException, ClassNotFoundException {
-// java.io.ObjectInputStream.GetField fields = s.readFields();
-// value = (char[])fields.get("value", null);
-// count = fields.get("count", 0);
-// }
-}