Difference between String, StringBuffer and StringBuilder

	String	StringBuffer	StringBuilder
Modification	immutable	Mutable	Mutable
Storage Area	Constant String Pool	Heap	Heap
Thread safe		Synchronized i.e. thread safe	Non-Synchronized i.e. not thread safe
Performance	Fast	slow	Fast
Speed on Concat too many strings	Slow and consumes more memory		Fast and consume less memory
	Overrides equals() method of Object class	Not such	Not such

 

• Simply use StringBuilder unless you really are trying to share a buffer between threads. StringBuilder is the unsynchronized (less overhead = more efficient) younger brother of the original synchronized StringBuffer class.
• Thread safe /Synchronized: Methods of Stringbuffer cannot be called by two or more threads simultaneously
• If content is fixed and is not changed frequently    - > STRING
• If content is not fixed and changes frequently :
  1. If thread safety required -> StringBuffer
  2. If thread safety not required -> String Builder