java.lang.StringBuffer

The StringBuffer is a thread safe, mutable sequence of characters. Its much the same as String however StringBuffer can be modified. Most commonly used properties of StringBuffer is the insert and the append method which more likely to be used by most programmers. As of Java 5, StringBuilder were introduced which is a much faster version of StringBuffer thus StringBuilder is more preferred,

StringBuffer Class Syntax

public final class StringBuffer
extends Object
implements Serializable, CharSequence

StringBuffer Compatibility Version

Requires JDK 1.0

StringBuffer Class Constructor

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

Method List Available for StringBuffer Class

Method Return Method Description
StringBuffer append(boolean b) Appends the string representation of the boolean argument to the sequence. A character sequence “true” or false is appended on the base string.
StringBuffer append(char c) Appends the string representation of the char argument to this sequence.
StringBuffer append(char[] str) Appends the string representation of the char array argument to this sequence.
StringBuffer append(char[] str, int offset, int len) Appends the string representation of a subarray of the char array argument to this sequence.
StringBuffer append(CharSequence s) Appends the specified CharSequence to this sequence.
StringBuffer append(CharSequence s, int start, int end) Appends a subsequence of the specified CharSequence to this sequence.
StringBuffer append(double d) Appends the string representation of the double argument to this sequence.
StringBuffer append(float f) Appends the string representation of the float argument to this sequence.
StringBuffer append(int i) Appends the string representation of the int argument to this sequence.
StringBuffer append(long lng) Appends the string representation of the long argument to this sequence.
StringBuffer append(Object obj) Appends the string representation of the Object argument.
StringBuffer append(String str) Appends the specified string to this character sequence.
StringBuffer append(StringBuffer sb) Appends the specified StringBuffer to this sequence.
StringBuffer appendCodePoint(int codePoint) Appends the string representation of the codePoint argument to this sequence.
int capacity() This method returns the current capacity of this character sequence.
char charAt(int index) Returns the char value in this sequence at the specified index.
int codePointAt(int index) Returns the character (Unicode code point) at the specified index.
int codePointBefore(int index) Returns the character (Unicode code point) before the specified index.
int codePointCount(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of this sequence.
StringBuffer delete(int start, int end) Removes the characters in a substring of this sequence.
StringBuffer deleteCharAt(int index) Removes the char at the specified position in this sequence.
void ensureCapacity(int minimumCapacity) Ensures that the capacity is at least equal to the specified minimum.
void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Characters are copied from this sequence into the destination character array dst.
int indexOf(String str) Returns the index within this string of the first occurrence of the specified substring.
int indexOf(String str, int fromIndex) Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
StringBuffer insert(int offset, boolean b) Inserts the string representation of the boolean argument into this sequence.
StringBuffer insert(int offset, char c) Inserts the string representation of the char argument into this sequence.
StringBuffer insert(int offset, char[] str) Inserts the string representation of the char array argument into this sequence.
StringBuffer insert(int index, char[] str, int offset, int len) Inserts the string representation of a subarray of the str array argument into this sequence.
StringBuffer insert(int dstOffset, CharSequence s) Inserts the specified CharSequence into this sequence.
StringBuffer insert(int dstOffset, CharSequence s, int start, int end) Inserts a subsequence of the specified CharSequence into this sequence.
StringBuffer insert(int offset, double d) Inserts the string representation of the double argument into this sequence.
StringBuffer insert(int offset, float f) Inserts the string representation of the float argument into this sequence.
StringBuffer insert(int offset, int i) Inserts the string representation of the second int argument into this sequence.
StringBuffer insert(int offset, long l) Inserts the string representation of the long argument into this sequence.
StringBuffer insert(int offset, Object obj) Inserts the string representation of the Object argument into this character sequence.
StringBuffer insert(int offset, String str) Inserts the string into this character sequence.
int lastIndexOf(String str) Returns the index within this string of the rightmost occurrence of the specified substring.
int lastIndexOf(String str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring.
int length() Returns the length (character count).
int offsetByCodePoints(int index, int codePointOffset) Returns the index within this sequence that is offset from the given index by codePointOffset code points.
StringBuffer replace(int start, int end, String str) Replaces the characters in a substring of this sequence with characters in the specified String.
StringBuffer reverse() Causes this character sequence to be replaced by the reverse of the sequence.
void setCharAt(int index, char ch) The character at the specified index is set to ch.
void setLength(int newLength) Sets the length of the character sequence.
CharSequence subSequence(int start, int end) Returns a new character sequence that is a subsequence of this sequence.
String substring(int start) Returns a new String that contains a subsequence of characters currently contained in this character sequence.
String substring(int start, int end) Returns a new String that contains a subsequence of characters currently contained in this sequence.
String toString() Returns a string representing the data in this sequence.
void trimToSize() Attempts to reduce storage used for the character sequence. If the buffer is larger than necessary to hold its current sequence of characters, then it may be resized to become more space efficient.