What is the purpose of the @Override annotation? [duplicate]

Question

Possible Duplicate:
When do you use Java's @Override annotation and why?

My question is very basic why we people use @Override annotation and what is the importance of this annotation?

In Old JDK why it not show as warning, but in latest JDK it required then Why..?

Answer 1

Suppose you have:

public class Foo {     public void bar(String x, String y) {} }  public class Foo2 extends Foo {     public void bar(String x, Object y) {} } 

You really meant Foo2.bar to override Foo.bar, but due to a mistake in the signature, it doesn't. If you use @Override you can get the compiler to detect the fault. It also indicates to any reading the code that this is overriding an existing method or implementing an interface - advising them about current behaviour and the possible impact of renaming the method.

Additionally, your compiler may give you a warning if a method overrides a method without specifying @Override, which means you can detect if someone has added a method with the same signature to a superclass without you being aware of it - you may not want to be overriding the new method, as your existing method may have different semantics. While @Override doesn't provide a way of "un-overriding" the method, it at least highlights the potential problem.

Answer 2

Just to make sure at compile time that we are really overriding the method, also adds good amount to the readability of code

@Override is there since JDK 1.5, so you might get warning in prior