Can I call instance method of a parent class directly in child class in Java?

Question

I have the below two classes. I'm wondering how I'm able to call the instance method of ClassA ie AMessage() in class B with out the instance of a ClassA or ClassB created?

I was thinking I should call instance method of ClassA ie AMessage() in class B as below:

new ClassA().AMessage(); //no compile error

new ClassB().Amessage(); //no compile error

Parent Class (ClassA.java)

public class ClassA {
    public void AMessage(){
        System.out.println("A Message");
    }
}

Child Class (ClassB.java)

public class ClassB extends ClassA{

        public void BMessage(){
            AMessage(); //no compile error
        }
        public static void main(String[] args){
            new ClassB().BMessage();
        }
    }

Answer 1

Use super keyword to call base class methods. Check this for reference - http://docs.oracle.com/javase/tutorial/java/IandI/super.html

public class ChildClass extends BaseClass{

        public static void main(String[] args){
            ChildClass obj =  new ChildClass();
            obj.Message();
        }

        public void Message(){
            super.Message();
        }
}

class BaseClass {
    public void Message(){
        System.out.println("Base Class called");
    }
}

Or you can do it like this as well -

public class ChildClass extends BaseClass{

        public static void main(String[] args){
            new ChildClass().Message();
        }
}

class BaseClass {
    public void Message(){
        System.out.println("Base Class called");
    }
}

Answer 2

yes you can call method directly instance method of parent class from child class object provided parent class method should be public

you can call in this way

new ClassB().AMessage();

it will also work

Answer 3

When a class extends another class, it automatically inherits the visible fields and methods of the base class. By visible I mean accessible members. Private members are not inherited. Learn more about inheritance in http://www.tutorialspoint.com/java/java_inheritance.htm

So if you have a class ClassA having a method AMessage like this :

public class ClassA{
        public void AMessage(){
            System.out.println("A message");
        }
   }

and ClassB which extends ClassA like this :

public class ClassB extends ClassA{

        public void BMessage(){
            AMessage(); 
        }
        public static void main(String[] args){
            new ClassB().BMessage();
        }
    }

ClassB automatically inherits members of ClassA ie they act as if they are members of ClassB itself. That's why we can call the instance method of ClassA inside ClassB without any instance, because they belong to ClassB as well. Also besides instance methods, you can call static methods like that as well. (But of course you can not call instance methods inside static methods.)

As an additional answer I would like to suggest that (although it is not related to the question but it is a good practice) you should not name any method of a class (instance or static) starting with a capital letter. It doesn't generate any compiler error if you still name it like that, but it affects the readability. I have written the names like that only to relate to your question.