Both StringBuffer and StringBuilder are two important classes in Java which represent mutable String i.e. the String object, whose value can be changed. Since String is Immutable in Java, any change or operation on String object e.g. converting it to upper or lower case, adding character, removing a character, or getting a substring, all results in a new String object. This can put a lot of pressure on the Garbage collector if your application generates lots of throws away String instances. To avoid this issue, Java designer presented initially StringBuffer class and later StringBuilder as mutable String. That's the main difference between String vs StringBuffer and StringBuilder and also one of the frequently asked Java questions for beginners.
Anyway, when
Anyway, when