Overriding Java code

Question

I am trying to understand what I am doing wrong with this code but I don't find the answer. Why it does not print anything in the compiler?

Please help. Thanks in advance.

public class ClassA {

     int x = 0;
     int y = 1;

     public void methodA() {

         System.out.println( "x is " + x + " , and y is " + y) ;
         System.out.println( "I am an instance of:  " + this.getClass().getName() ) ;
     }
}

class ClassB extends ClassA {

    int z = 3; 

    public static void main(String[] args) {

        ClassB obj1 = new ClassB();
        obj1.methodA();

    }
}

`Why it does not print anything in the compiler?` Because the compiler ***compiles*** the code. You need to ***run*** it to see the output. — BackSlash, Aug 06 '14 at 13:56
What are you expecting, and what actually happens? Your question is unclear. — Jon Skeet, Aug 06 '14 at 13:56
Because the compiler doesn't approve of your lack of proper formatting. — , Aug 06 '14 at 13:57
@Kon - The OP isn't *overriding* anything as the question says :) — TheLostMind, Aug 06 '14 at 13:57
@madhawapriyashantha as of now yes. OP might trying to learn method overriding :) — Suresh Atta, Aug 06 '14 at 14:05

Suresh Atta · Answer 1 · 2014-08-06T14:09:20.797

Because you are only compiling , not running the code. Run it. It will print the result to console for sure.

No Overriding concept there in your code as of now. Every Children is Parent. You'll have access to that method and it prints the implementation of Parent (ClassA).

Coming to the concept of Overriding, if you want to see the implementation of methodA() in ClassB, then you need to Override it in ClassB and provide implementation related to ClassB.

score 1 · Answer 2 · answered Aug 06 '14 at 13:59

1

I don't have any problems, everything works as it should. It prints:

x is 0 , and y is 1
I am an instance of:  test.ClassB

Process finished with exit code 0

Check your IDE.

answered Aug 06 '14 at 13:59

PaintedRed

1,398
5
19
30

2

Did the OP state he is using an IDE? – BackSlash Aug 06 '14 at 13:59

score 0 · Answer 3 · answered Aug 06 '14 at 14:35

0

The class with main method should be public

class ClassA {

 int x = 0;
 int y = 1;

 public void methodA() {
 System.out.println( "x is " + x + " , and y is " + y) ;
 System.out.println( "I am an instance of:  " + this.getClass().getName() ) ;
     }
}

public class ClassB extends ClassA { int z = 3;

public static void main(String[] args) {
    ClassB obj1 = new ClassB();
    obj1.methodA();

}

}

This works

answered Aug 06 '14 at 14:35

Sarfaraz

45
4

_The class with main method should be public_ No, this is not mandatory. A class which has a main method can be run even if it doesn't have an access modifier. – BackSlash Aug 06 '14 at 14:39
@BackSlash plz check this: http://stackoverflow.com/questions/12524322/what-if-main-method-is-inside-non-public-class-of-java-file – Sarfaraz Aug 06 '14 at 14:45
Please check this and try it yourself: http://ideone.com/Qlsq6m Look at the class definition. It's not declared as `public class`, it compiles and runs fine. – BackSlash Aug 06 '14 at 14:48
@BackSlash, I agree with you. We have to make sure we are executing the correct class (i.e. don't confuse it with the file name) – Sarfaraz Aug 06 '14 at 15:36

Overriding Java code

3 Answers3