AnonymousClass

public class MyClass {
    private int mSomeVar;

    private SomeOtherClass mSomeOtherClass = new SomeOtherClass(){
        @Override
        public void someOtherClassMethod() {
            someMethod();
        }

        @Override
        public void anotherTest() {
            mSomeVar = 123;
        }
    };

    private void someMethod() {
        mSomeVar = 0;
    }
}

abstract class SomeOtherClass {
       public abstract void someOtherClassMethod();

       public abstract void anotherTest();
}