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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package java.lang;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.io.Serial;
import java.io.Serializable;
import java.io.StreamCorruptedException;
import jdk.internal.vm.annotation.IntrinsicCandidate;
/**
* A thread-safe, mutable sequence of characters.
* A string buffer is like a {@link String}, but can be modified. At any
* point in time it contains some particular sequence of characters, but
* the length and content of the sequence can be changed through certain
* method calls.
*
* 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 {@code StringBuffer} are the
* {@code append} and {@code 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
* {@code append} method always adds these characters at the end
* of the buffer; the {@code insert} method adds the characters at
* a specified point.
*
* For example, if {@code z} refers to a string buffer object
* whose current contents are {@code "start"}, then
* the method call {@code z.append("le")} would cause the string
* buffer to contain {@code "startle"}, whereas
* {@code z.insert(4, "le")} would alter the string buffer to
* contain {@code "starlet"}.
*
* In general, if sb refers to an instance of a {@code StringBuffer},
* then {@code sb.append(x)} has the same effect as
* {@code 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.
* Note that while {@code StringBuffer} is designed to be safe to use
* concurrently from multiple threads, if the constructor or the
* {@code append} or {@code insert} operation is passed a source sequence
* that is shared across threads, the calling code must ensure
* that the operation has a consistent and unchanging view of the source
* sequence for the duration of the operation.
* This could be satisfied by the caller holding a lock during the
* operation's call, by using an immutable source sequence, or by not
* sharing the source sequence across threads.
*
* 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.
*
* Unless otherwise noted, passing a {@code null} argument to a constructor
* or method in this class will cause a {@link NullPointerException} to be
* thrown.
*
* As of release JDK 5, this class has been supplemented with an equivalent
* class designed for use by a single thread, {@link StringBuilder}. The
* {@code 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.
*
* @apiNote
* {@code StringBuffer} implements {@code Comparable} but does not override
* {@link Object#equals equals}. Thus, the natural ordering of {@code StringBuffer}
* is inconsistent with equals. Care should be exercised if {@code StringBuffer}
* objects are used as keys in a {@code SortedMap} or elements in a {@code SortedSet}.
* See {@link Comparable}, {@link java.util.SortedMap SortedMap}, or
* {@link java.util.SortedSet SortedSet} for more information.
*
* @author Arthur van Hoff
* @see java.lang.StringBuilder
* @see java.lang.String
* @since 1.0
*/
public final class StringBuffer
extends AbstractStringBuilder
implements Serializable, Comparable, CharSequence
{
/**
* A cache of the last value returned by toString. Cleared
* whenever the StringBuffer is modified.
*/
private transient String toStringCache;
/** use serialVersionUID from JDK 1.0.2 for interoperability */
@Serial
static final long serialVersionUID = 3388685877147921107L;
/**
* Constructs a string buffer with no characters in it and an
* initial capacity of 16 characters.
*/
@IntrinsicCandidate
public StringBuffer() {
super(16);
}
/**
* Constructs a string buffer with no characters in it and
* the specified initial capacity.
*
* @param capacity the initial capacity.
* @throws NegativeArraySizeException if the {@code capacity}
* argument is less than {@code 0}.
*/
@IntrinsicCandidate
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
* {@code 16} plus the length of the string argument.
*
* @param str the initial contents of the buffer.
*/
@IntrinsicCandidate
public StringBuffer(String str) {
super(str);
}
/**
* Constructs a string buffer that contains the same characters
* as the specified {@code CharSequence}. The initial capacity of
* the string buffer is {@code 16} plus the length of the
* {@code CharSequence} argument.
*
* @param seq the sequence to copy.
* @since 1.5
*/
public StringBuffer(CharSequence seq) {
super(seq);
}
/**
* Compares two {@code StringBuffer} instances lexicographically. This method
* follows the same rules for lexicographical comparison as defined in the
* {@linkplain java.lang.CharSequence#compare(java.lang.CharSequence,
* java.lang.CharSequence) CharSequence.compare(this, another)} method.
*
*
* For finer-grained, locale-sensitive String comparison, refer to
* {@link java.text.Collator}.
*
* @implNote
* This method synchronizes on {@code this}, the current object, but not
* {@code StringBuffer another} with which {@code this StringBuffer} is compared.
*
* @param another the {@code StringBuffer} to be compared with
*
* @return the value {@code 0} if this {@code StringBuffer} contains the same
* character sequence as that of the argument {@code StringBuffer}; a negative integer
* if this {@code StringBuffer} is lexicographically less than the
* {@code StringBuffer} argument; or a positive integer if this {@code StringBuffer}
* is lexicographically greater than the {@code StringBuffer} argument.
*
* @since 11
*/
@Override
public synchronized int compareTo(StringBuffer another) {
return super.compareTo(another);
}
@Override
public synchronized int length() {
return count;
}
@Override
public synchronized int capacity() {
return super.capacity();
}
@Override
public synchronized void ensureCapacity(int minimumCapacity) {
super.ensureCapacity(minimumCapacity);
}
/**
* @since 1.5
*/
@Override
public synchronized void trimToSize() {
super.trimToSize();
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @see #length()
*/
@Override
public synchronized void setLength(int newLength) {
toStringCache = null;
super.setLength(newLength);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @see #length()
*/
@Override
public synchronized char charAt(int index) {
return super.charAt(index);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized int codePointAt(int index) {
return super.codePointAt(index);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized int codePointBefore(int index) {
return super.codePointBefore(index);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized int codePointCount(int beginIndex, int endIndex) {
return super.codePointCount(beginIndex, endIndex);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized int offsetByCodePoints(int index, int codePointOffset) {
return super.offsetByCodePoints(index, codePointOffset);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized void getChars(int srcBegin, int srcEnd, char[] dst,
int dstBegin)
{
super.getChars(srcBegin, srcEnd, dst, dstBegin);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @see #length()
*/
@Override
public synchronized void setCharAt(int index, char ch) {
toStringCache = null;
super.setCharAt(index, ch);
}
@Override
public synchronized StringBuffer append(Object obj) {
toStringCache = null;
super.append(String.valueOf(obj));
return this;
}
@Override
@IntrinsicCandidate
public synchronized StringBuffer append(String str) {
toStringCache = null;
super.append(str);
return this;
}
/**
* Appends the specified {@code StringBuffer} to this sequence.
*
* The characters of the {@code StringBuffer} argument are appended,
* in order, to the contents of this {@code StringBuffer}, increasing the
* length of this {@code StringBuffer} by the length of the argument.
* If {@code sb} is {@code null}, then the four characters
* {@code "null"} are appended to this {@code StringBuffer}.
*
* Let n be the length of the old character sequence, the one
* contained in the {@code StringBuffer} just prior to execution of the
* {@code 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 {@code sb}.
*
* This method synchronizes on {@code this}, the destination
* object, but does not synchronize on the source ({@code sb}).
*
* @param sb the {@code StringBuffer} to append.
* @return a reference to this object.
* @since 1.4
*/
public synchronized StringBuffer append(StringBuffer sb) {
toStringCache = null;
super.append(sb);
return this;
}
/**
* @since 1.8
*/
@Override
synchronized StringBuffer append(AbstractStringBuilder asb) {
toStringCache = null;
super.append(asb);
return this;
}
/**
* Appends the specified {@code CharSequence} to this
* sequence.
*
* The characters of the {@code 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 {@code this}, the destination
* object, but does not synchronize on the source ({@code s}).
*
*
If {@code s} is {@code null}, then the four characters
* {@code "null"} are appended.
*
* @param s the {@code CharSequence} to append.
* @return a reference to this object.
* @since 1.5
*/
@Override
public synchronized StringBuffer append(CharSequence s) {
toStringCache = null;
super.append(s);
return this;
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized StringBuffer append(CharSequence s, int start, int end)
{
toStringCache = null;
super.append(s, start, end);
return this;
}
@Override
public synchronized StringBuffer append(char[] str) {
toStringCache = null;
super.append(str);
return this;
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized StringBuffer append(char[] str, int offset, int len) {
toStringCache = null;
super.append(str, offset, len);
return this;
}
@Override
public synchronized StringBuffer append(boolean b) {
toStringCache = null;
super.append(b);
return this;
}
@Override
@IntrinsicCandidate
public synchronized StringBuffer append(char c) {
toStringCache = null;
super.append(c);
return this;
}
@Override
@IntrinsicCandidate
public synchronized StringBuffer append(int i) {
toStringCache = null;
super.append(i);
return this;
}
/**
* @since 1.5
*/
@Override
public synchronized StringBuffer appendCodePoint(int codePoint) {
toStringCache = null;
super.appendCodePoint(codePoint);
return this;
}
@Override
public synchronized StringBuffer append(long lng) {
toStringCache = null;
super.append(lng);
return this;
}
@Override
public synchronized StringBuffer append(float f) {
toStringCache = null;
super.append(f);
return this;
}
@Override
public synchronized StringBuffer append(double d) {
toStringCache = null;
super.append(d);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized StringBuffer delete(int start, int end) {
toStringCache = null;
super.delete(start, end);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized StringBuffer deleteCharAt(int index) {
toStringCache = null;
super.deleteCharAt(index);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized StringBuffer replace(int start, int end, String str) {
toStringCache = null;
super.replace(start, end, str);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized String substring(int start) {
return substring(start, count);
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.4
*/
@Override
public synchronized CharSequence subSequence(int start, int end) {
return super.substring(start, end);
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized String substring(int start, int end) {
return super.substring(start, end);
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
* @since 1.2
*/
@Override
public synchronized StringBuffer insert(int index, char[] str, int offset,
int len)
{
toStringCache = null;
super.insert(index, str, offset, len);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized StringBuffer insert(int offset, Object obj) {
toStringCache = null;
super.insert(offset, String.valueOf(obj));
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized StringBuffer insert(int offset, String str) {
toStringCache = null;
super.insert(offset, str);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized StringBuffer insert(int offset, char[] str) {
toStringCache = null;
super.insert(offset, str);
return this;
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public StringBuffer insert(int dstOffset, CharSequence s) {
// Note, synchronization achieved via invocations of other StringBuffer methods
// after narrowing of s to specific type
// Ditto for toStringCache clearing
super.insert(dstOffset, s);
return this;
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
* @since 1.5
*/
@Override
public synchronized StringBuffer insert(int dstOffset, CharSequence s,
int start, int end)
{
toStringCache = null;
super.insert(dstOffset, s, start, end);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public StringBuffer insert(int offset, boolean b) {
// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
// after conversion of b to String by super class method
// Ditto for toStringCache clearing
super.insert(offset, b);
return this;
}
/**
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
@Override
public synchronized StringBuffer insert(int offset, char c) {
toStringCache = null;
super.insert(offset, c);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public StringBuffer insert(int offset, int i) {
// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
// after conversion of i to String by super class method
// Ditto for toStringCache clearing
super.insert(offset, i);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public StringBuffer insert(int offset, long l) {
// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
// after conversion of l to String by super class method
// Ditto for toStringCache clearing
super.insert(offset, l);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public StringBuffer insert(int offset, float f) {
// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
// after conversion of f to String by super class method
// Ditto for toStringCache clearing
super.insert(offset, f);
return this;
}
/**
* @throws StringIndexOutOfBoundsException {@inheritDoc}
*/
@Override
public StringBuffer insert(int offset, double d) {
// Note, synchronization achieved via invocation of StringBuffer insert(int, String)
// after conversion of d to String by super class method
// Ditto for toStringCache clearing
super.insert(offset, d);
return this;
}
/**
* @since 1.4
*/
@Override
public int indexOf(String str) {
// Note, synchronization achieved via invocations of other StringBuffer methods
return super.indexOf(str);
}
/**
* @since 1.4
*/
@Override
public synchronized int indexOf(String str, int fromIndex) {
return super.indexOf(str, fromIndex);
}
/**
* @since 1.4
*/
@Override
public int lastIndexOf(String str) {
// Note, synchronization achieved via invocations of other StringBuffer methods
return lastIndexOf(str, count);
}
/**
* @since 1.4
*/
@Override
public synchronized int lastIndexOf(String str, int fromIndex) {
return super.lastIndexOf(str, fromIndex);
}
/**
* @since 1.0.2
*/
@Override
public synchronized StringBuffer reverse() {
toStringCache = null;
super.reverse();
return this;
}
@Override
@IntrinsicCandidate
public synchronized String toString() {
if (toStringCache == null) {
return toStringCache =
isLatin1() ? StringLatin1.newString(value, 0, count)
: StringUTF16.newString(value, 0, count);
}
return new String(toStringCache);
}
/**
* 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.
*/
@Serial
private static final ObjectStreamField[] serialPersistentFields =
{
new ObjectStreamField("value", char[].class),
new ObjectStreamField("count", Integer.TYPE),
new ObjectStreamField("shared", Boolean.TYPE),
};
/**
* The {@code writeObject} method is called to write the state of the
* {@code StringBuffer} to a stream.
*
* @param s the {@code ObjectOutputStream} to which data is written
* @throws IOException if an I/O error occurs
*/
@Serial
private synchronized void writeObject(ObjectOutputStream s)
throws IOException {
ObjectOutputStream.PutField fields = s.putFields();
char[] val = new char[capacity()];
if (isLatin1()) {
StringLatin1.getChars(value, 0, count, val, 0);
} else {
StringUTF16.getChars(value, 0, count, val, 0);
}
fields.put("value", val);
fields.put("count", count);
fields.put("shared", false);
s.writeFields();
}
/**
* The {@code readObject} method is called to restore the state of the
* {@code StringBuffer} from a stream.
*
* @param s the {@code ObjectInputStream} from which data is read
* @throws IOException if an I/O error occurs
* @throws ClassNotFoundException if a serialized class cannot be loaded
*/
@Serial
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException {
ObjectInputStream.GetField fields = s.readFields();
char[] val = (char[])fields.get("value", null);
int c = fields.get("count", 0);
if (c < 0 || c > val.length) {
throw new StreamCorruptedException("count value invalid");
}
initBytes(val, 0, val.length);
count = c;
// ignore shared field
}
synchronized void getBytes(byte dst[], int dstBegin, byte coder) {
super.getBytes(dst, dstBegin, coder);
}
}