Why we use @Override while implementing a method from Interface ? Does it really Override the method?

Question

While we use any method from the interface it asks us to override all unimplemented method. also we are using '@Override' annotation while implementing the method. Does it really called overriding ? because interface contains only method definition(no executable code). The interface is say,

public interface ITestListener extends ITestNGListener {
  void onTestStart(ITestResult result);
  public void onTestSuccess(ITestResult result);
  public void onTestFailure(ITestResult result);
  public void onTestSkipped(ITestResult result);
  public void onTestFailedButWithinSuccessPercentage(ITestResult result);
}

and the implementing class is

public class TestNGTestBase implements ITestListener{  @Override
    public void onTestStart(ITestResult result) {
//xyz

    }                                                                                              @Override
    public void onTestSuccess(ITestResult result) { /// xyz} @Override
    public void onTestSkipped(ITestResult result) {


    }

    @Override
    public void onTestFailedButWithinSuccessPercentage(ITestResult result) {
        // TODO Auto-generated method stub

    }}

also why is this mandatory to override all the methods in the interface ?

yes it is overriding. And the `@Override` notation makes sure that the method is really an overriden one and would create a compile time error if the method signature of any of these methods would change and there wouldn´t be a method fitting that signature anymore. — SomeJavaGuy, Mar 03 '16 at 07:27

Luc Geven · Answer 1 · 2016-03-03T07:42:48.110

1

Yes the method is overriding from the superclass. This notation would create a compile time error if the method signature of any of these methods would change.

Overriding is a feature that is available while using Inheritance.

It is used when a class that extends from another class wants to use most of the feature of the parent class and wants to implement specific functionality in certain cases.

edited Mar 03 '16 at 07:42

answered Mar 03 '16 at 07:37

Luc Geven

164
12

score 0 · Answer 2 · answered Mar 03 '16 at 09:27

@Overriding ensures the method is a correct override and gives compile time error if its not a valid override. It is not mandatory to override all methods of an interface in a class,you need to declare the class "abstract" in this scenario.

But if you want a concrete class(which can be instantiated) to implement an interface,you will need to implement all methods of your interface in this concrete class

Why we use @Override while implementing a method from Interface ? Does it really Override the method?

2 Answers2