StringBuffer java :-
1) StringBuffer class is like same as String.
2) StringBuffer class is thread-safe means method are synchronized.
3) StringBuffer class is mutable sequence of characters.
4) Main method in StringBuffer class are append and insert method.
5) Through the insert method you can insert string after any index of the string.
6) There are four constructors in StringBuffer class.
public StringBuffer(int capacity)
public StringBuffer(String str)
public StringBuffer(CharSequence seq)