Summary: Ctors | Methods | Inherited Methods | [Expand All]

Since: API Level 1

public final class

StringBuffer

extends Object
implements Serializable Appendable CharSequence

java.lang.Object
↳	java.lang.StringBuffer

Class Overview

A modifiable sequence of characters for use in creating strings, where all accesses are synchronized. This class has mostly been replaced by StringBuilder because this synchronization is rarely useful. This class is mainly used to interact with legacy APIs that expose it.

For particularly complex string-building needs, consider Formatter.

The majority of the modification methods on this class return this so that method calls can be chained together. For example: new StringBuffer("a").append("b").append("c").toString().

Summary

Public Constructors
	StringBuffer() Constructs a new StringBuffer using the default capacity which is 16.
	StringBuffer(int capacity) Constructs a new StringBuffer using the specified capacity.
	StringBuffer(String string) Constructs a new StringBuffer containing the characters in the specified string.
	StringBuffer(CharSequence cs) Constructs a StringBuffer and initializes it with the content from the specified `CharSequence`.

Public Methods
synchronized StringBuffer	append(char[] chars, int start, int length) Adds the specified sequence of characters to the end of this buffer.
StringBuffer	append(double d) Adds the string representation of the specified double to the end of this StringBuffer.
StringBuffer	append(boolean b) Adds the string representation of the specified boolean to the end of this StringBuffer.
StringBuffer	append(long l) Adds the string representation of the specified long to the end of this StringBuffer.
StringBuffer	append(float f) Adds the string representation of the specified float to the end of this StringBuffer.
synchronized StringBuffer	append(char[] chars) Adds the character array to the end of this buffer.
StringBuffer	append(int i) Adds the string representation of the specified integer to the end of this StringBuffer.
synchronized StringBuffer	append(StringBuffer sb) Adds the specified StringBuffer to the end of this buffer.
synchronized StringBuffer	append(CharSequence s) Appends the specified CharSequence to this buffer.
synchronized StringBuffer	append(char ch) Adds the specified character to the end of this buffer.
synchronized StringBuffer	append(String string) Adds the specified string to the end of this buffer.
synchronized StringBuffer	append(CharSequence s, int start, int end) Appends the specified subsequence of the CharSequence to this buffer.
synchronized StringBuffer	append(Object obj) Adds the string representation of the specified object to the end of this StringBuffer.
StringBuffer	appendCodePoint(int codePoint) Appends the string representation of the specified Unicode code point to the end of this buffer.
int	capacity() Returns the number of characters that can be held without growing.
synchronized char	charAt(int index) Retrieves the character at the `index`.
synchronized int	codePointAt(int index) Retrieves the Unicode code point value at the `index`.
synchronized int	codePointBefore(int index) Retrieves the Unicode code point value that precedes the `index`.
synchronized int	codePointCount(int beginIndex, int endIndex) Calculates the number of Unicode code points between `start` and `end`.
synchronized StringBuffer	delete(int start, int end) Deletes a range of characters.
synchronized StringBuffer	deleteCharAt(int location) Deletes the character at the specified offset.
synchronized void	ensureCapacity(int min) Ensures that this object has a minimum capacity available before requiring the internal buffer to be enlarged.
synchronized void	getChars(int start, int end, char[] buffer, int idx) Copies the requested sequence of characters to the `char[]` passed starting at `idx`.
synchronized int	indexOf(String subString, int start) Searches for the index of the specified character.
int	indexOf(String string) Searches for the first index of the specified character.
synchronized StringBuffer	insert(int index, CharSequence s, int start, int end) Inserts the specified subsequence into this buffer at the specified index.
StringBuffer	insert(int index, int i) Inserts the string representation of the specified integer into this buffer at the specified offset.
StringBuffer	insert(int index, double d) Inserts the string representation of the specified into this buffer double at the specified offset.
synchronized StringBuffer	insert(int index, char[] chars, int start, int length) Inserts the specified subsequence of characters into this buffer at the specified index.
synchronized StringBuffer	insert(int index, String string) Inserts the string into this buffer at the specified offset.
StringBuffer	insert(int index, long l) Inserts the string representation of the specified long into this buffer at the specified offset.
StringBuffer	insert(int index, Object obj) Inserts the string representation of the specified object into this buffer at the specified offset.
StringBuffer	insert(int index, float f) Inserts the string representation of the specified float into this buffer at the specified offset.
synchronized StringBuffer	insert(int index, char ch) Inserts the character into this buffer at the specified offset.
synchronized StringBuffer	insert(int index, char[] chars) Inserts the character array into this buffer at the specified offset.
synchronized StringBuffer	insert(int index, CharSequence s) Inserts the specified CharSequence into this buffer at the specified index.
StringBuffer	insert(int index, boolean b) Inserts the string representation of the specified boolean into this buffer at the specified offset.
int	lastIndexOf(String string) Searches for the last index of the specified character.
synchronized int	lastIndexOf(String subString, int start) Searches for the index of the specified character.
int	length() The current length.
synchronized int	offsetByCodePoints(int index, int codePointOffset) Returns the index that is offset `codePointOffset` code points from `index`.
synchronized StringBuffer	replace(int start, int end, String string) Replaces the characters in the specified range with the contents of the specified string.
synchronized StringBuffer	reverse() Reverses the order of characters in this buffer.
synchronized void	setCharAt(int index, char ch) Sets the character at the `index`.
synchronized void	setLength(int length) Sets the current length to a new value.
synchronized CharSequence	subSequence(int start, int end) Returns a `CharSequence` of the subsequence from the `start` index to the `end` index.
synchronized String	substring(int start) Returns the String value of the subsequence from the `start` index to the current end.
synchronized String	substring(int start, int end) Returns the String value of the subsequence from the `start` index to the `end` index.
synchronized String	toString() Returns the current String representation.
synchronized void	trimToSize() Trims off any extra capacity beyond the current length.

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Called before the object's memory is reclaimed by the VM.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

From interface java.lang.Appendable

From interface java.lang.CharSequence

Public Constructors

public StringBuffer ()

Since: API Level 1

Constructs a new StringBuffer using the default capacity which is 16.

public StringBuffer (int capacity)

Since: API Level 1

Constructs a new StringBuffer using the specified capacity.

Parameters

capacity	the initial capacity.

public StringBuffer (String string)

Since: API Level 1

Constructs a new StringBuffer containing the characters in the specified string. The capacity of the new buffer will be the length of the String plus the default capacity.

Parameters

string	the string content with which to initialize the new instance.

Throws

NullPointerException	if `string` is `null`.

public StringBuffer (CharSequence cs)

Since: API Level 1

Constructs a StringBuffer and initializes it with the content from the specified CharSequence. The capacity of the new buffer will be the length of the CharSequence plus the default capacity.

Parameters

cs	the content to initialize the instance.

Throws

NullPointerException	if `cs` is `null`.

Public Methods

public synchronized StringBuffer append (char[] chars, int start, int length)

Since: API Level 1

Adds the specified sequence of characters to the end of this buffer.

Parameters

chars	the character array to append.
start	the starting offset.
length	the number of characters.

Returns

this StringBuffer.

Throws

ArrayIndexOutOfBoundsException	if `length < 0` , `start < 0` or `start + length > chars.length`.
NullPointerException	if `chars` is `null`.

public StringBuffer append (double d)

Since: API Level 1

Adds the string representation of the specified double to the end of this StringBuffer.

Parameters

d	the double to append.

Returns

this StringBuffer.

public StringBuffer append (boolean b)

Since: API Level 1

Adds the string representation of the specified boolean to the end of this StringBuffer.

If the argument is true the string "true" is appended, otherwise the string "false" is appended.

Parameters

b	the boolean to append.

Returns

this StringBuffer.

public StringBuffer append (long l)

Since: API Level 1

Adds the string representation of the specified long to the end of this StringBuffer.

Parameters

l	the long to append.

Returns

this StringBuffer.

public StringBuffer append (float f)

Since: API Level 1

Adds the string representation of the specified float to the end of this StringBuffer.

Parameters

f	the float to append.

Returns

this StringBuffer.

public synchronized StringBuffer append (char[] chars)

Since: API Level 1

Adds the character array to the end of this buffer.

Parameters

chars	the character array to append.

Returns

this StringBuffer.

Throws

NullPointerException	if `chars` is `null`.

public StringBuffer append (int i)

Since: API Level 1

Adds the string representation of the specified integer to the end of this StringBuffer.

Parameters

i	the integer to append.

Returns

this StringBuffer.

public synchronized StringBuffer append (StringBuffer sb)

Since: API Level 1

Adds the specified StringBuffer to the end of this buffer.

If the specified StringBuffer is null the string "null" is appended, otherwise the contents of the specified StringBuffer is appended.

Parameters

sb	the StringBuffer to append (may be null).

Returns

this StringBuffer.

public synchronized StringBuffer append (CharSequence s)

Since: API Level 1

Appends the specified CharSequence to this buffer.

If the specified CharSequence is null the string "null" is appended, otherwise the contents of the specified CharSequence is appended.

Parameters

s	the CharSequence to append.

Returns

this StringBuffer.

public synchronized StringBuffer append (char ch)

Since: API Level 1

Adds the specified character to the end of this buffer.

Parameters

ch	the character to append.

Returns

this StringBuffer.

public synchronized StringBuffer append (String string)

Since: API Level 1

Adds the specified string to the end of this buffer.

If the specified string is null the string "null" is appended, otherwise the contents of the specified string is appended.

Parameters

string	the string to append (may be null).

Returns

this StringBuffer.

public synchronized StringBuffer append (CharSequence s, int start, int end)

Since: API Level 1

Appends the specified subsequence of the CharSequence to this buffer.

If the specified CharSequence is null, then the string "null" is used to extract a subsequence.

Parameters

s	the CharSequence to append.
start	the inclusive start index.
end	the exclusive end index.

Returns

this StringBuffer.

Throws

IndexOutOfBoundsException	if `start` or `end` are negative, `start` is greater than `end` or `end` is greater than the length of `s`.

public synchronized StringBuffer append (Object obj)

Since: API Level 1

Adds the string representation of the specified object to the end of this StringBuffer.

If the specified object is null the string "null" is appended, otherwise the objects toString is used to get its string representation.

Parameters

obj	the object to append (may be null).

Returns

this StringBuffer.

public StringBuffer appendCodePoint (int codePoint)

Since: API Level 1

Appends the string representation of the specified Unicode code point to the end of this buffer.

The code point is converted to a char[] as defined by toChars(int).

Parameters

codePoint	the Unicode code point to encode and append.

Returns

this StringBuffer.

public int capacity ()

Since: API Level 1

Returns the number of characters that can be held without growing.

Returns

the capacity

public synchronized char charAt (int index)

Since: API Level 1

Retrieves the character at the index.

Parameters

index	the index of the character to retrieve.

Returns

the char value.

public synchronized int codePointAt (int index)

Since: API Level 1

Retrieves the Unicode code point value at the index.

Parameters

index	the index to the `char` code unit.

Returns

the Unicode code point value.

public synchronized int codePointBefore (int index)

Since: API Level 1

Retrieves the Unicode code point value that precedes the index.

Parameters

index	the index to the `char` code unit within this object.

Returns

the Unicode code point value.

public synchronized int codePointCount (int beginIndex, int endIndex)

Since: API Level 1

Calculates the number of Unicode code points between start and end.

Parameters

beginIndex	the inclusive beginning index of the subsequence.
endIndex	the exclusive end index of the subsequence.

Returns

the number of Unicode code points in the subsequence.

public synchronized StringBuffer delete (int start, int end)

Since: API Level 1

Deletes a range of characters.

Parameters

start	the offset of the first character.
end	the offset one past the last character.

Returns

this StringBuffer.

Throws

StringIndexOutOfBoundsException	if `start < 0`, `start > end` or `end > length()`.

public synchronized StringBuffer deleteCharAt (int location)

Since: API Level 1

Deletes the character at the specified offset.

Parameters

location	the offset of the character to delete.

Returns

this StringBuffer.

Throws

StringIndexOutOfBoundsException	if `location < 0` or `location >= length()`

public synchronized void ensureCapacity (int min)

Since: API Level 1

Ensures that this object has a minimum capacity available before requiring the internal buffer to be enlarged. The general policy of this method is that if the minimumCapacity is larger than the current capacity(), then the capacity will be increased to the largest value of either the minimumCapacity or the current capacity multiplied by two plus two. Although this is the general policy, there is no guarantee that the capacity will change.

Parameters

min	the new minimum capacity to set.

public synchronized void getChars (int start, int end, char[] buffer, int idx)

Since: API Level 1

Copies the requested sequence of characters to the char[] passed starting at idx.

Parameters

start	the starting offset of characters to copy.
end	the ending offset of characters to copy.
buffer	the destination character array.
idx	the starting offset in the character array.

Throws

IndexOutOfBoundsException	if `start < 0`, `end > length()`, `start > end`, `index < 0`, `end - start > buffer.length - index`

public synchronized int indexOf (String subString, int start)

Since: API Level 1

Searches for the index of the specified character. The search for the character starts at the specified offset and moves towards the end.

Parameters

subString	the string to find.
start	the starting offset.

Returns

the index of the specified character, -1 if the character isn't found

public int indexOf (String string)

Since: API Level 1

Searches for the first index of the specified character. The search for the character starts at the beginning and moves towards the end.

Parameters

string	the string to find.

Returns

the index of the specified character, -1 if the character isn't found.

public synchronized StringBuffer insert (int index, CharSequence s, int start, int end)

Since: API Level 1

Inserts the specified subsequence into this buffer at the specified index.

If the specified CharSequence is null, the string "null" is inserted, otherwise the contents of the CharSequence.

Parameters

index	The index at which to insert.
s	The char sequence to insert.
start	The inclusive start index in the char sequence.
end	The exclusive end index in the char sequence.

Returns

this buffer.

Throws

IndexOutOfBoundsException	if `index` is negative or greater than the current length, `start` or `end` are negative, `start` is greater than `end` or `end` is greater than the length of `s`.

public StringBuffer insert (int index, int i)

Since: API Level 1

Inserts the string representation of the specified integer into this buffer at the specified offset.

Parameters

index	the index at which to insert.
i	the integer to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public StringBuffer insert (int index, double d)

Since: API Level 1

Inserts the string representation of the specified into this buffer double at the specified offset.

Parameters

index	the index at which to insert.
d	the double to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public synchronized StringBuffer insert (int index, char[] chars, int start, int length)

Since: API Level 1

Inserts the specified subsequence of characters into this buffer at the specified index.

Parameters

index	the index at which to insert.
chars	the character array to insert.
start	the starting offset.
length	the number of characters.

Returns

this buffer.

Throws

NullPointerException	if `chars` is `null`.
StringIndexOutOfBoundsException	if `length < 0`, `start < 0`, `start + length > chars.length`, `index < 0` or `index > length()`

public synchronized StringBuffer insert (int index, String string)

Since: API Level 1

Inserts the string into this buffer at the specified offset.

If the specified string is null, the string "null" is inserted, otherwise the contents of the string is inserted.

Parameters

index	the index at which to insert.
string	the string to insert (may be null).

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public StringBuffer insert (int index, long l)

Since: API Level 1

Inserts the string representation of the specified long into this buffer at the specified offset.

Parameters

index	the index at which to insert.
l	the long to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public StringBuffer insert (int index, Object obj)

Since: API Level 1

Inserts the string representation of the specified object into this buffer at the specified offset.

If the specified object is null, the string "null" is inserted, otherwise the objects toString method is used to get its string representation.

Parameters

index	the index at which to insert.
obj	the object to insert (may be null).

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public StringBuffer insert (int index, float f)

Since: API Level 1

Inserts the string representation of the specified float into this buffer at the specified offset.

Parameters

index	the index at which to insert.
f	the float to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public synchronized StringBuffer insert (int index, char ch)

Since: API Level 1

Inserts the character into this buffer at the specified offset.

Parameters

index	the index at which to insert.
ch	the character to insert.

Returns

this buffer.

Throws

ArrayIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public synchronized StringBuffer insert (int index, char[] chars)

Since: API Level 1

Inserts the character array into this buffer at the specified offset.

Parameters

index	the index at which to insert.
chars	the character array to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.
NullPointerException	if `chars` is `null`.

public synchronized StringBuffer insert (int index, CharSequence s)

Since: API Level 1

Inserts the specified CharSequence into this buffer at the specified index.

If the specified CharSequence is null, the string "null" is inserted, otherwise the contents of the CharSequence.

Parameters

index	The index at which to insert.
s	The char sequence to insert.

Returns

this buffer.

Throws

IndexOutOfBoundsException	if `index < 0` or `index > length()`.

public StringBuffer insert (int index, boolean b)

Since: API Level 1

Inserts the string representation of the specified boolean into this buffer at the specified offset.

Parameters

index	the index at which to insert.
b	the boolean to insert.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `index < 0` or `index > length()`.

public int lastIndexOf (String string)

Since: API Level 1

Searches for the last index of the specified character. The search for the character starts at the end and moves towards the beginning.

Parameters

string	the string to find.

Returns

the index of the specified character, -1 if the character isn't found.

Throws

NullPointerException	if `string` is `null`.

public synchronized int lastIndexOf (String subString, int start)

Since: API Level 1

Searches for the index of the specified character. The search for the character starts at the specified offset and moves towards the beginning.

Parameters

subString	the string to find.
start	the starting offset.

Returns

the index of the specified character, -1 if the character isn't found.

public int length ()

Since: API Level 1

The current length.

Returns

the number of characters contained in this instance.

public synchronized int offsetByCodePoints (int index, int codePointOffset)

Since: API Level 1

Returns the index that is offset codePointOffset code points from index.

Parameters

index	the index to calculate the offset from.
codePointOffset	the number of code points to count.

Returns

the index that is codePointOffset code points away from index.

public synchronized StringBuffer replace (int start, int end, String string)

Since: API Level 1

Replaces the characters in the specified range with the contents of the specified string.

Parameters

start	the inclusive begin index.
end	the exclusive end index.
string	the string that will replace the contents in the range.

Returns

this buffer.

Throws

StringIndexOutOfBoundsException	if `start` or `end` are negative, `start` is greater than `end` or `end` is greater than the length of `s`.

public synchronized StringBuffer reverse ()

Since: API Level 1

Reverses the order of characters in this buffer.

Returns

this buffer.

public synchronized void setCharAt (int index, char ch)

Since: API Level 1

Sets the character at the index.

Parameters

index	the zero-based index of the character to replace.
ch	the character to set.

public synchronized void setLength (int length)

Since: API Level 1

Sets the current length to a new value. If the new length is larger than the current length, then the new characters at the end of this object will contain the char value of .

Parameters

length	the new length of this StringBuffer.

public synchronized CharSequence subSequence (int start, int end)

Since: API Level 1

Returns a CharSequence of the subsequence from the start index to the end index.

Parameters

start	the inclusive start index to begin the subsequence.
end	the exclusive end index to end the subsequence.

Returns

a CharSequence containing the subsequence.

public synchronized String substring (int start)

Since: API Level 1

Returns the String value of the subsequence from the start index to the current end.

Parameters

start	the inclusive start index to begin the subsequence.

Returns

a String containing the subsequence.

public synchronized String substring (int start, int end)

Since: API Level 1

Returns the String value of the subsequence from the start index to the end index.

Parameters

start	the inclusive start index to begin the subsequence.
end	the exclusive end index to end the subsequence.

Returns

a String containing the subsequence.

public synchronized String toString ()

Since: API Level 1

Returns the current String representation.

Returns

a String containing the characters in this instance.

public synchronized void trimToSize ()

Since: API Level 1

Trims off any extra capacity beyond the current length. Note, this method is NOT guaranteed to change the capacity of this object.

Interfaces

Classes

Enums

Exceptions

Errors

StringBuffer

Class Overview

See Also

Summary

Public Constructors

public StringBuffer ()

public StringBuffer (int capacity)

Parameters

public StringBuffer (String string)

Parameters

Throws

public StringBuffer (CharSequence cs)

Parameters

Throws

Public Methods

public synchronized StringBuffer append (char[] chars, int start, int length)

Parameters

Returns

Throws

public StringBuffer append (double d)

Parameters

Returns

See Also

public StringBuffer append (boolean b)

Parameters

Returns

See Also

public StringBuffer append (long l)

Parameters

Returns

See Also

public StringBuffer append (float f)

Parameters

Returns

See Also

public synchronized StringBuffer append (char[] chars)

Parameters

Returns

Throws

public StringBuffer append (int i)

Parameters

Returns

See Also

public synchronized StringBuffer append (StringBuffer sb)

Parameters

Returns

public synchronized StringBuffer append (CharSequence s)

Parameters

Returns

public synchronized StringBuffer append (char ch)

Parameters

Returns

See Also

public synchronized StringBuffer append (String string)

Parameters

Returns

public synchronized StringBuffer append (CharSequence s, int start, int end)

Parameters

Returns

Throws

public synchronized StringBuffer append (Object obj)

Parameters

Returns

See Also

public StringBuffer appendCodePoint (int codePoint)

Parameters

Returns

See Also

public int capacity ()

Returns

See Also

public synchronized char charAt (int index)

Parameters

Returns

public synchronized int codePointAt (int index)