Use methods declared in implementation that are not defined in interface

Question

I have a class defined by an interface

public interface Test {
    void testMethod();
}

Test test = new TestImpl();

public class TestImpl implements Test {         


        

Answer 1

You can call it if you cast to the implementing class, the one that implements that method In short:

Test test = new TestImpl();

// ... and later / somewhere else

((TestImpl) test).anotherMethod();