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Java String Buffer

String creates a string of fixed length, while StringBuffer creates a string of flexible length, that can be modified in term of both length and contents. We can insert characters, sub-string in the middle or in the end of the StringBuffer.

Syntax: In Java, StringBuffer can be declared as follows:

StringBuffer sb = new StringBuffer("Java Programming");

Java StringBuffer methods

The Java StringBuffer class defines a number of methods that allow us to manipulate a string.

List of Java String Buffer methods:
S.No. Method Syntax Description
insert() s1.insert(n,s2) Insert string s2 at n position in s1.
append() s1.append('x') Add any character or string at end of s1.
charAt() s1.charAt(6) Return the 6+1th character from s1.
subString() s1.subString(6)
s1.subString(n,m)
Return sub-string, starting from 6th character to end. It will work on both String as well as StringBuffer. Also, we can specify starting (n) to end (m) position.
indexOf() s1.indexOf('x') Return the index number of x character in s1.
indexOf() s1.indexOf('x', n) Return the index number of x character in s1 starting from nth position.
setLength() s1.setLength(n) Sets the length limit of string s1 to n. If n>s1.length() than spaces are added.
reverse() s.reverse() Reverse the characters stored in StringBuffer.
replace() s.replace(5,7,"was") Replace character at position 5, 6th index and insert "was" in it.
delete() s.delete(4,7) Delete characters on 4, 5 and 6th index.
deleteCharAt() s.deleteCharAt(0) It delete a single specified character.