Summary: Ctors | Methods | Inherited Methods

StringBuffer

public final class StringBuffer
extends Object implements Appendable, CharSequence, Comparable<StringBuffer>, Serializable

java.lang.Object
↳	java.lang.StringBuffer

A thread-safe, mutable sequence of characters. A string buffer is like a 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 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. Note that while StringBuffer is designed to be safe to use concurrently from multiple threads, if the constructor or the append or 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 null argument to a constructor or method in this class will cause a 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, 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.

See also:

StringBuilder
String

Summary

Public constructors
`StringBuffer()` Constructs a string buffer with no characters in it and an initial capacity of 16 characters.
`StringBuffer(int capacity)` Constructs a string buffer with no characters in it and the specified initial capacity.
`StringBuffer(CharSequence seq)` Constructs a string buffer that contains the same characters as the specified `CharSequence`.
`StringBuffer(String str)` Constructs a string buffer initialized to the contents of the specified string.

Public methods
`StringBuffer`	`append(boolean b)`
`StringBuffer`	`append(long lng)`
`StringBuffer`	`append(char c)` Appends the specified character to this `Appendable`.
`StringBuffer`	`append(Object obj)`
`StringBuffer`	`append(char[] str, int offset, int len)`
`StringBuffer`	`append(double d)`
`StringBuffer`	`append(char[] str)`
`StringBuffer`	`append(String str)`
`StringBuffer`	`append(StringBuffer sb)` Appends the specified `StringBuffer` to this sequence.
`StringBuffer`	`append(float f)`
`StringBuffer`	`append(int i)`
`StringBuffer`	`append(CharSequence s, int start, int end)` Appends a subsequence of the specified character sequence to this `Appendable`.
`StringBuffer`	`append(CharSequence s)` Appends the specified `CharSequence` to this sequence.
`StringBuffer`	`appendCodePoint(int codePoint)`
`int`	`capacity()`
`char`	`charAt(int index)` Returns the `char` value at the specified index.
`IntStream`	`chars()` Returns a stream of `int` zero-extending the `char` values from this sequence.
`int`	`codePointAt(int index)`
`int`	`codePointBefore(int index)`
`int`	`codePointCount(int beginIndex, int endIndex)`
`IntStream`	`codePoints()` Returns a stream of code point values from this sequence.
`int`	`compareTo(StringBuffer another)` Compares two `StringBuffer` instances lexicographically.
`StringBuffer`	`delete(int start, int end)`
`StringBuffer`	`deleteCharAt(int index)`
`void`	`ensureCapacity(int minimumCapacity)`
`void`	`getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)`
`int`	`indexOf(String str)`
`int`	`indexOf(String str, int fromIndex)`
`StringBuffer`	`insert(int offset, char[] str)`
`StringBuffer`	`insert(int offset, float f)`
`StringBuffer`	`insert(int dstOffset, CharSequence s)`
`StringBuffer`	`insert(int offset, char c)`
`StringBuffer`	`insert(int offset, long l)`
`StringBuffer`	`insert(int index, char[] str, int offset, int len)`
`StringBuffer`	`insert(int offset, int i)`
`StringBuffer`	`insert(int offset, String str)`
`StringBuffer`	`insert(int offset, double d)`
`StringBuffer`	`insert(int dstOffset, CharSequence s, int start, int end)`
`StringBuffer`	`insert(int offset, boolean b)`
`StringBuffer`	`insert(int offset, Object obj)`
`int`	`lastIndexOf(String str, int fromIndex)`
`int`	`lastIndexOf(String str)`
`int`	`length()` Returns the length of this character sequence.
`int`	`offsetByCodePoints(int index, int codePointOffset)`
`StringBuffer`	`replace(int start, int end, String str)`
`StringBuffer`	`reverse()`
`void`	`setCharAt(int index, char ch)`
`void`	`setLength(int newLength)`
`CharSequence`	`subSequence(int start, int end)` Returns a `CharSequence` that is a subsequence of this sequence.
`String`	`substring(int start, int end)`
`String`	`substring(int start)`
`String`	`toString()` Returns a string representation of the object.
`void`	`trimToSize()`

Inherited methods

From class java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface java.lang.Appendable

`abstract Appendable`	`append(char c)` Appends the specified character to this `Appendable`.
`abstract Appendable`	`append(CharSequence csq, int start, int end)` Appends a subsequence of the specified character sequence to this `Appendable`.
`abstract Appendable`	`append(CharSequence csq)` Appends the specified character sequence to this `Appendable`.

From interface java.lang.CharSequence

`abstract char`	`charAt(int index)` Returns the `char` value at the specified index.
`default IntStream`	`chars()` Returns a stream of `int` zero-extending the `char` values from this sequence.
`default IntStream`	`codePoints()` Returns a stream of code point values from this sequence.
`static int`	`compare(CharSequence cs1, CharSequence cs2)` Compares two `CharSequence` instances lexicographically.
`default boolean`	`isEmpty()` Returns `true` if this character sequence is empty.
`abstract int`	`length()` Returns the length of this character sequence.
`abstract CharSequence`	`subSequence(int start, int end)` Returns a `CharSequence` that is a subsequence of this sequence.
`abstract String`	`toString()` Returns a string containing the characters in this sequence in the same order as this sequence.

From interface java.lang.Comparable

abstract int

compareTo(StringBuffer o)

Compares this object with the specified object for order.

Parameters
`s`	`CharSequence`: The character sequence from which a subsequence will be appended. If `csq` is `null`, then characters will be appended as if `csq` contained the four characters `"null"`.
`start`	`int`: The index of the first character in the subsequence
`end`	`int`: The index of the character following the last character in the subsequence

Parameters
`start`	`int`: the start index, inclusive
`end`	`int`: the end index, exclusive

StringBuffer

Summary

Public constructors

Public methods

Inherited methods

Public constructors

StringBuffer

StringBuffer

StringBuffer

StringBuffer

Public methods

append

append

append

append

append

append

append

append

append

append

append

append

append

appendCodePoint

capacity

charAt

chars

codePointAt

codePointBefore

codePointCount

codePoints

compareTo

Implementation Note:

delete

deleteCharAt

ensureCapacity

getChars

indexOf

indexOf

insert

insert

insert

insert

insert

insert

insert

insert

insert

insert

insert

insert

lastIndexOf

lastIndexOf

length

offsetByCodePoints

replace

reverse

setCharAt

setLength

subSequence

substring

substring

toString

trimToSize