Question

I can’t remember the name of this concept.

  public interface MainInterface {
      public void method1();
      public void method2();
 }

  void testMethod() {
        methodMain(new MainInterface() {

            @Override
            public void method1() {
                System.out.println("This is method1");
            }

            @Override
            public void method2() {
                System.out.println("This is method2");
            }
        });
    }

   void methodMain(MainInterface mi) {
        mi.method1();
        mi.method2();
   }

• I create the instance of MainInterface without giving the name of object
• I implement the interface methods
• Then pass the instance with unknown name to methodMain.

What is this concept and how exactly it works?

Answer 1

You have created an instance of an Anonymous Inner Class (i.e. a class without a name).