ParentChildTest.java

public class ParentChildTest{



    public static void main(String[] args){

        Parent parent = new Parent();

        parent.onDraw();



        ChildA childA = new ChildA();

        childA.onDraw();

        

        ChildB childB = new ChildB();

        childB.onDraw();



        Parent parentca =  new ChildA();

        parentca.onDraw();

    }





    public static class Parent{



        public Parent(){

            System.out.println("Parent()");

        }

        

        public void onDraw(){

            System.out.println("onDraw: Parent");

        }

    }



    public static class ChildA extends Parent{



        public ChildA(){

            System.out.println("ChildA()");

        }

        

        public void onDraw(){

            System.out.println("onDraw: ChildA");

        }

    }



    public static class ChildB extends Parent{



        public ChildB(){

            System.out.println("ChildB()");

        }

        

        public void onDraw(){

            System.out.println("onDraw: ChildB");

        }

    }

}

$ java ParentChildTest
Parent()
onDraw: Parent
Parent()
ChildA()
onDraw: ChildA
Parent()
ChildB()
onDraw: ChildB
Parent()
ChildA()
onDraw: ChildA