What is super?

Posted in: Advantages of Immutability,Autoboxing in Java,Core Java

super is a keyword which is used to access the method or member variables from the superclass. If a method hides one of the member variables in its superclass, the method can refer to the hidden variable through the use of the super keyword. In the same way, if a method overrides one of the methods in its superclass, the method can invoke the overridden method through the use of the super keyword.
Note:

• You can only go back one level.
• In the constructor, if you use super(), it must be the very first code, and you cannot access any this.xxx variables or methods to compute its parameters.

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Advantages of Immutability

Posted in: Advantages of Immutability

1) Immutable objects are automatically thread-safe, the overhead caused due to use of synchronisation is avoided.
2) Once created the state of the immutable object can not be changed so there is no possibility of them getting into an inconsistent state.
3) The references to the immutable objects can be easily shared or cached without having to copy or clone them as there state can not be changed ever after construction.
4) The best use of the immutable objects is as the keys of a map.