Java immutable object--java concurrent programming practice

An object that cannot be modified after the creation state is called an immutable object . Immutable objects are inherently thread-safe. Their constants (fields) are created in the constructor. Since their state cannot be modified, these constants will never change.

immutable objects are always thread-safe .

An object is immutable only if it satisfies the following state;

• Its state cannot be modified after it has been created;

• All fields are final type;

• It is created correctly (the escape of this reference does not occur during creation).
  

Java immutable object--java concurrent programming practice