Difference between StringBuffer, String and StringBuilder in Java

1) String is immutable while StringBuffer and StringBuilder is mutable object.

2) StringBuffer is synchronized while StringBuilder is not which makes StringBuilder faster than StringBuffer.

3) Concatenation operator "+" is internal implemented using either StringBuffer or StringBuilder.

4) Use String if you require immutability, use Stringbuffer in java if you need mutable + thread-safety and use StringBuilder in Java if you require mutable + without thread-safety.