How to call a method

[newcoder1010 3]

Hello,

 

I have my java as follows:

 public class Test_Final {

	 public void test_non_final () {
	  System.out.println("hello");}

	}

public class Test_Final_Caller extends Test_Final{ // separate file
		 public static void main(String args[]) {
			 Test_Final_Caller S1 = new  Test_Final_Caller();
			  System.out.println(S1.test_final_method()); // error here
			  System.out.println(S1.test_non_final());    // error here



		 }
}

I am not able to print hello from Test_Final_Caller. Can you advise?

[Ingolme 794]

What does the error message say?

 

Your functions don't return anything, so there's nothing to print out to the system.

 

Use this function instead for testing:

public static void main(String args[]) {
  Test_Final_Caller S1 = new Test_Final_Caller()
  S1.test_non_final();
}

[newcoder1010 3]

Now, it is working. Thanks.

[davej 244]

I'm not sure what you are trying to do but you should probably read some online tutorials on inheritance, upcasting, downcasting, and polymorphism.

[newcoder1010 3]

Trying to go thru tutorial in http://www.w3schools.in/java-tutorial/aggregation/. Is it a typo in your site?

 public class stud{
    public static void main(String args[]){
    college a = new college();
    college b = new univ();
    a.move();
    b.move();
   }
}

4th line, Instead of

college b = new univ();

, should it be

univ b = new univ();

?

[davej 244]

Actually w3schools.in is unaffiliated with w3schools.com (at least AFAIK)

 

The question you are asking is related to polymorphism.

 

A subclass can be declared as a superclass, as in the following...

Bicycle bike01 = new Bicycle(20, 10, 1);
Bicycle bike02 = new MountainBike(20, 10, 5, "Dual");
Bicycle bike03 = new RoadBike(40, 20, 8, 23);

Assuming the MountainBike and RoadBike classes both extend (inherit) the Bicycle class.

 

See...

 

https://docs.oracle.com/javase/tutorial/java/IandI/polymorphism.html

[newcoder1010 3]

Thank you so much. I have long way to go. Yes, I am going thru online tutorials.