Reference:Java.lang.StringBuffer

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java.lang
public final class java.lang.StringBuffer

java.lang.Object
	java.lang.StringBuffer	Serializable Appendable CharSequence

StringBuffer is a variable size contiguous indexable array of characters. The length of the StringBuffer is the number of characters it contains. The capacity of the StringBuffer is the number of characters it can hold.

Characters may be inserted at any position up to the length of the StringBuffer, increasing the length of the StringBuffer. Characters at any position in the StringBuffer may be replaced, which does not affect the StringBuffer length.

The capacity of a StringBuffer may be specified when the StringBuffer is created. If the capacity of the StringBuffer is exceeded, the capacity is increased.

See Also

• String
• StringBuilder

[edit] Summary

[edit] Public Constructors

					StringBuffer ()
					Constructs a new StringBuffer using the default capacity.
					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 and the default capacity.
					StringBuffer (CharSequence cs)
					Constructs a StringBuffer and initializes it with the characters in the CharSequence.

[edit] Public Methods

				StringBuffer	append (double d)
					Adds the string representation of the specified double to the end of this StringBuffer.
	synchronized			StringBuffer	append (CharSequence s)
					Appends the CharSequence to this buffer.
				StringBuffer	append (long l)
					Adds the string representation of the specified long to the end of this StringBuffer.
				StringBuffer	append (int i)
					Adds the string representation of the specified integer to the end of this StringBuffer.
				StringBuffer	append (boolean b)
					Adds the string representation of the specified boolean to the end of this StringBuffer.
	synchronized			StringBuffer	append (Object obj)
					Adds the string representation of the specified object to the end of this StringBuffer.
	synchronized			StringBuffer	append (char ch)
					Adds the specified character to the end of this StringBuffer.
	synchronized			StringBuffer	append (char[] chars)
					Adds the character array to the end of this StringBuffer.
	synchronized			StringBuffer	append (String string)
					Adds the specified string 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, int start, int length)
					Adds the specified sequence of characters to the end of this StringBuffer.
	synchronized			StringBuffer	append (CharSequence s, int start, int end)
					Appends the subsequence of the CharSequence to this buffer.
	synchronized			StringBuffer	append (StringBuffer sb)
					Adds the specified StringBuffer to the end of this StringBuffer.
				StringBuffer	appendCodePoint (int codePoint)
					Appends the encoded Unicode code point to this object.
				int	capacity ()
					Answers the number of characters this StringBuffer can hold without growing.
	synchronized			char	charAt (int index)
					Answers the character at the specified offset in this StringBuffer.
	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 beginIndex and endIndex.
	synchronized			StringBuffer	delete (int start, int end)
					Deletes a range of characters.
	synchronized			StringBuffer	deleteCharAt (int location)
					Deletes a single character
	synchronized			void	ensureCapacity (int min)
					Ensures that this StringBuffer can hold the specified number of characters without growing.
	synchronized			void	getChars (int start, int end, char[] buffer, int idx)
					Copies the specified characters in this StringBuffer to the character array starting at the specified offset in the character array.
	synchronized			int	indexOf (String subString, int start)
					Searches in this StringBuffer for the index of the specified character.
				int	indexOf (String string)
					Searches in this StringBuffer for the first index of the specified character.
				StringBuffer	insert (int index, Object obj)
					Inserts the string representation of the specified object at the specified offset in this StringBuffer.
	synchronized			StringBuffer	insert (int index, String string)
					Inserts the string at the specified offset in this StringBuffer.
	synchronized			StringBuffer	insert (int index, char[] chars)
					Inserts the character array at the specified offset in this StringBuffer.
				StringBuffer	insert (int index, boolean b)
					Inserts the string representation of the specified boolean at the specified offset in this StringBuffer.
				StringBuffer	insert (int index, double d)
					Inserts the string representation of the specified double at the specified offset in this StringBuffer.
	synchronized			StringBuffer	insert (int index, char ch)
					Inserts the character at the specified offset in this StringBuffer.
				StringBuffer	insert (int index, float f)
					Inserts the string representation of the specified float at the specified offset in this StringBuffer.
				StringBuffer	insert (int index, int i)
					Inserts the string representation of the specified integer at the specified offset in this StringBuffer.
	synchronized			StringBuffer	insert (int index, CharSequence s)
					Inserts the CharSequence into this buffer at the index.
	synchronized			StringBuffer	insert (int index, CharSequence s, int start, int end)
					Inserts the CharSequence into this buffer at the index.
	synchronized			StringBuffer	insert (int index, char[] chars, int start, int length)
					Inserts the specified sequence of characters at the specified offset in this StringBuffer.
				StringBuffer	insert (int index, long l)
					Inserts the string representation of the specified long at the specified offset in this StringBuffer.
				int	lastIndexOf (String string)
					Searches in this StringBuffer for the last index of the specified character.
	synchronized			int	lastIndexOf (String subString, int start)
					Searches in this StringBuffer for the index of the specified character.
				int	length ()
					The current length of this object.
	synchronized			int	offsetByCodePoints (int index, int codePointOffset)
					Returns the index within this object that is offset from index by codePointOffset code points.
	synchronized			StringBuffer	replace (int start, int end, String string)
					Replace a range of characters with the characters in the specified String.
	synchronized			StringBuffer	reverse ()
					Reverses the order of characters in this StringBuffer.
	synchronized			void	setCharAt (int index, char ch)
					Sets the character at the specified offset in this StringBuffer.
	synchronized			void	setLength (int length)
					Sets the length of this StringBuffer to the specified length.
	synchronized			CharSequence	subSequence (int start, int end)
					Copies a range of characters into a new String.
	synchronized			String	substring (int start, int end)
					Copies a range of characters into a new String.
	synchronized			String	substring (int start)
					Copies a range of characters into a new String.
	synchronized			String	toString ()
					Answers the contents of this StringBuffer.
	synchronized			void	trimToSize ()
					Trims the storage capacity of this buffer down to the size of the current character sequence.

[edit] Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

[edit] Methods inherited from interface java.lang.CharSequence

charAt, length, subSequence, toString

[edit] Methods inherited from interface java.lang.Appendable

append, append, append

[edit] Details

[edit] Public Constructors

[edit] public StringBuffer()

Constructs a new StringBuffer using the default capacity.

[edit] public StringBuffer(int capacity)

Constructs a new StringBuffer using the specified capacity.

Parameters

capacity	the initial capacity

[edit] public StringBuffer(String string)

Constructs a new StringBuffer containing the characters in the specified string and the default capacity.

Parameters

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

Throws

NullPointerException	on supplying a null value of string

[edit] public StringBuffer(CharSequence cs)

Constructs a StringBuffer and initializes it with the characters in the CharSequence.

Parameters

cs	The CharSequence to initialize the instance.

Throws

NullPointerException	if the cs parameter is null.

[edit] Public Methods

[edit] public StringBuffer append(double d)

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

Parameters

d	the double

Returns

• this StringBuffer

[edit] public synchronized StringBuffer append(CharSequence s)

Appends the CharSequence to this buffer. If the CharSequence is null, then the string "null" is appended.

Parameters

s	The CharSequence to append.

Returns

• A reference to this object.

[edit] public StringBuffer append(long l)

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

Parameters

l	the long

Returns

• this StringBuffer

[edit] public StringBuffer append(int i)

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

Parameters

i	the integer

Returns

• this StringBuffer

[edit] public StringBuffer append(boolean b)

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

Parameters

b	the boolean

Returns

• this StringBuffer

[edit] public synchronized StringBuffer append(Object obj)

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

Parameters

obj	the object

Returns

• this StringBuffer

[edit] public synchronized StringBuffer append(char ch)

Adds the specified character to the end of this StringBuffer.

Parameters

ch	a character

Returns

• this StringBuffer

[edit] public synchronized StringBuffer append(char[] chars)

Adds the character array to the end of this StringBuffer.

Parameters

chars	the character array

Returns

• this StringBuffer

Throws

NullPointerException	when chars is null

[edit] public synchronized StringBuffer append(String string)

Adds the specified string to the end of this StringBuffer.

Parameters

string	the string

Returns

• this StringBuffer

[edit] public StringBuffer append(float f)

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

Parameters

f	the float

Returns

• this StringBuffer

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

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

Parameters

chars	a character array
start	the starting offset
length	the number of characters

Returns

• this StringBuffer

Throws

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

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

Appends the subsequence of the CharSequence to this buffer. If the CharSequence is null, then the string "null" is used to extract a subsequence.

Parameters

s	The CharSequence to append.
start	The inclusive start index of the subsequence of the CharSequence.
end	The exclusive end index of the subsequence of the CharSequence.

Returns

• A reference to this object.

Throws

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

[edit] public synchronized StringBuffer append(StringBuffer sb)

Adds the specified StringBuffer to the end of this StringBuffer.

Parameters

sb	the StringBuffer

Returns

• this StringBuffer

[edit] public StringBuffer appendCodePoint(int codePoint)

Appends the encoded Unicode code point to this object. The code point is converted to a char[] as defined by toChars(int).

Parameters

codePoint	The Unicode code point to encode and append.

Returns

• A reference to this object.

See Also

• toChars(int)

[edit] public int capacity()

Answers the number of characters this StringBuffer can hold without growing.

Returns

• the capacity of this StringBuffer

See Also

• ensureCapacity(int)
• length()

[edit] public synchronized char charAt(int index)

Answers the character at the specified offset in this StringBuffer.

Parameters

index	the zero-based index in this StringBuffer

Returns

• the character at the index

Throws

IndexOutOfBoundsException	when index < 0 or index >= length()

[edit] public synchronized int codePointAt(int index)

Retrieves the Unicode code point value at the index.

Parameters

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

Returns

• The Unicode code point value.

Throws

IndexOutOfBoundsException	if index is negative or greater than or equal to length().

See Also

• Character
• codePointAt(char[], int, int)

[edit] public synchronized int codePointBefore(int index)

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.

Throws

IndexOutOfBoundsException	if index is less than 1 or greater than length().

See Also

• Character
• codePointBefore(char[], int, int)

[edit] public synchronized int codePointCount(int beginIndex, int endIndex)

Calculates the number of Unicode code points between beginIndex and endIndex.

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.

Throws

IndexOutOfBoundsException	if beginIndex is negative or greater than endIndex or endIndex is greater than length().

[edit] public synchronized StringBuffer delete(int start, int end)

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	when start < 0, start > end or end > length()

[edit] public synchronized StringBuffer deleteCharAt(int location)

Deletes a single character

Parameters

location	the offset of the character to delete

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when location < 0 or location >= length()

[edit] public synchronized void ensureCapacity(int min)

Ensures that this StringBuffer can hold the specified number of characters without growing.

Parameters

min	the minimum number of elements that this StringBuffer will hold before growing

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

Copies the specified characters in this StringBuffer to the character array starting at the specified offset in the character array.

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	when start < 0, end > length(), start > end, index < 0, end - start > buffer.length - index
NullPointerException	when buffer is null

[edit] public synchronized int indexOf(String subString, int start)

Searches in this StringBuffer 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 in this StringBuffer of the specified character, -1 if the character isn't found

See Also

• lastIndexOf(String, int)

[edit] public int indexOf(String string)

Searches in this StringBuffer 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 in this StringBuffer of the specified character, -1 if the character isn't found

See Also

• lastIndexOf(String)

[edit] public StringBuffer insert(int index, Object obj)

Inserts the string representation of the specified object at the specified offset in this StringBuffer.

Parameters

index	the index at which to insert
obj	the object to insert

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public synchronized StringBuffer insert(int index, String string)

Inserts the string at the specified offset in this StringBuffer.

Parameters

index	the index at which to insert
string	the string to insert

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

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

Inserts the character array at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()
NullPointerException	when chars is null

[edit] public StringBuffer insert(int index, boolean b)

Inserts the string representation of the specified boolean at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public StringBuffer insert(int index, double d)

Inserts the string representation of the specified double at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

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

Inserts the character at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

ArrayIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public StringBuffer insert(int index, float f)

Inserts the string representation of the specified float at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public StringBuffer insert(int index, int i)

Inserts the string representation of the specified integer at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public synchronized StringBuffer insert(int index, CharSequence s)

Inserts the CharSequence into this buffer at the index. If CharSequence is null, then the string "null" is inserted.

Parameters

index	The index of this buffer to insert the sequence.
s	The CharSequence to insert.

Returns

• A reference to this object.

Throws

IndexOutOfBoundsException	if the index is invalid.

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

Inserts the CharSequence into this buffer at the index. If CharSequence is null, then the string "null" is inserted.

Parameters

index	The index of this buffer to insert the sequence.
s	The CharSequence to insert.
start	The inclusive start index of the subsequence of the CharSequence.
end	The exclusive end index of the subsequence of the CharSequence.

Returns

• A reference to this object.

Throws

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

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

Inserts the specified sequence of characters at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

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

[edit] public StringBuffer insert(int index, long l)

Inserts the string representation of the specified long at the specified offset in this StringBuffer.

Parameters

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

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when index < 0 or index > length()

[edit] public int lastIndexOf(String string)

Searches in this StringBuffer 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 in this StringBuffer of the specified character, -1 if the character isn't found

Throws

NullPointerException	if the string parameter is null.

See Also

• lastIndexOf(java.lang.String)

[edit] public synchronized int lastIndexOf(String subString, int start)

Searches in this StringBuffer 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 in this StringBuffer of the specified character, -1 if the character isn't found

See Also

• indexOf(String, int)

[edit] public int length()

The current length of this object.

Returns

• the number of characters in this StringBuffer

[edit] public synchronized int offsetByCodePoints(int index, int codePointOffset)

Returns the index within this object that is offset from index by codePointOffset code points.

Parameters

index	The index within this object to calculate the offset from.
codePointOffset	The number of code points to count.

Returns

• The index within this object that is the offset.

Throws

IndexOutOfBoundsException	if index is negative or greater than length() or if there aren't enough code points before or after index to match codePointOffset.

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

Replace a range of characters with the characters in the specified String.

Parameters

start	the offset of the first character
end	the offset one past the last character
string	a String

Returns

• this StringBuffer

Throws

StringIndexOutOfBoundsException	when start < 0 or start > end

[edit] public synchronized StringBuffer reverse()

Reverses the order of characters in this StringBuffer.

Returns

• this StringBuffer

[edit] public synchronized void setCharAt(int index, char ch)

Sets the character at the specified offset in this StringBuffer.

Parameters

index	the zero-based index in this StringBuffer
ch	the character

Throws

IndexOutOfBoundsException	when index < 0 or index >= length()

[edit] public synchronized void setLength(int length)

Sets the length of this StringBuffer to the specified length. If there are more than length characters in this StringBuffer, the characters at end are lost. If there are less than length characters in the StringBuffer, the additional characters are set to \\u0000.

Parameters

length	the new length of this StringBuffer

Throws

IndexOutOfBoundsException	when length < 0

See Also

• length()

[edit] public synchronized CharSequence subSequence(int start, int end)

Copies a range of characters into a new String.

Parameters

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

Returns

• a new String containing the characters from start to end - 1

Throws

IndexOutOfBoundsException	when start < 0, start > end or end > length()

[edit] public synchronized String substring(int start, int end)

Copies a range of characters into a new String.

Parameters

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

Returns

• a new String containing the characters from start to end - 1

Throws

StringIndexOutOfBoundsException	when start < 0, start > end or end > length()

[edit] public synchronized String substring(int start)

Copies a range of characters into a new String.

Parameters

start	the offset of the first character

Returns

• a new String containing the characters from start to the end of the string

Throws

StringIndexOutOfBoundsException	when start < 0 or start > length()

[edit] public synchronized String toString()

Answers the contents of this StringBuffer.

Returns

• a String containing the characters in this StringBuffer

[edit] public synchronized void trimToSize()

Trims the storage capacity of this buffer down to the size of the current character sequence. Execution of this method may change the results returned by the capacity() method, but this is not required.

[edit] References

• Original documentation page for Android SDK build m5-rc15e - 14 apr 2008 17:27