String & StringBuffer & StringBuilder

**** String ****

-> String is immutable ( once created can not be changed )object.
The object created as a String is stored in the Constant String Pool .
Every immutable object in Java is thread safe ,that implies String is also thread safe .
String can not be used by two threads simultaneously.
String once assigned can not be changed.

**** StringBuffer ***

-> StringBuffer is mutable means one can change the value of the object .
The object created through StringBuffer is stored in the heap .
StringBuffer has the same methods as the StringBuilder ,
but each method in StringBuffer is synchronized that is StringBuffer is thread safe .

****** StringBuilder ****

-> StringBuilder is same as the StringBuffer ,
that is it stores the object in heap and it can also be modified .
The main difference between the StringBuffer and StringBuilder is that StringBuilder is also not thread safe.
StringBuilder is fast as it is not thread safe .

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