What is the use of Override annotation in Java When do we use it

Question

I recently came across the Java's @Override annotation. Why do we use it ? and What are the best practices for using it ? 

Do we mark every single overridden method with the @Overrideannotation or Are there certain programming situations that call for using the @Override ? Also are there situations where we should never use the @Override?

Answer 1

I think it is most useful as a compile-time reminder that the intention of the method is to override a parent method. As an example:

protected boolean displaySensitiveInformation() {
  return false;
}

You will often see something like the above method that overrides a method in the base class. This is an important implementation detail of this class -- we don't want sensitive information to be displayed.

Suppose this method is changed in the parent class to

protected boolean displaySensitiveInformation(Context context) {
  return true;
}

This change will not cause any compile time errors or warnings - but it completely changes the intended behavior of the subclass.

To answer your question: you should use the @Override annotation if the lack of a method with the same signature in a superclass is indicative of a bug.

Answer 2

@Override annotation is used when we override a method in sub class. 

Using @Override annotation while overriding a method is considered as a best practice for coding in java because of the following two advantages:

•  If programmer makes any mistake such as wrong method name, wrong parameter types while overriding, you would get a compile time error. As by using this annotation you instruct compiler that you are overriding this method. If you don’t use the annotation then the sub class method would behave as a new method (not the overriding method) in sub class.

• It improves the readability of the code. So if you change the signature of overridden method then all the sub classes that overrides the particular method would throw a compilation error, which would eventually help you to change the signature in the sub classes.