class

Overriding Fields

In this example we shall show you how to override a super class field in a subclass. To override a super class field in a subclass we have performed the following steps:

  • We have created a class, A that has a final int field set to 1, and an int field. It has an int getAttr() that prints a message and returns the int field.
  • Class B extends A and also has a final int field set to 2. It also has a method int getAttr() that calls its superclass getAttr() and returns its int field.
  • We create a new instance of A and call its getAttr() method.
  • We also create a new instance of B class and call its getAttr() method.
  • Then we create a new A object, using B constructor and use the object’s getAttr() method.
  • In order that B object is initialized A constructor is first called,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;

class A {

    final int field = 1;
    int x;

    int getAttr() {

  System.out.println("In OA.getAttr");

  return field;
    }
}

class B extends A {

    final int field = 2;

    int getAttr() {

  System.out.println("In OB.getAttr");

  super.getAttr(); // Just to show flow of control

  return field;
    }
}

public class OverridingFields {

    public static void main(String[] av) {

  System.out.println("A's getAttr returns: " + new A().getAttr());

  System.out.println("B's getAttr returns: " + new B().getAttr());
     

  // Declared as A, instantiated as B, so gets B's version of things.

  A c = new B();

  System.out.println("C's version of getAttr returns: "


    + c.getAttr());
    }
}

Output:

In A.getAttr
A's getAttr returns: 1
In B.getAttr
In A.getAttr
B's getAttr returns: 2
In B.getAttr
In A.getAttr
C's version of getAttr returns: 2

  
This was an example of how to override a super class field in a subclass in Java.

Want to know how to develop your skillset to become a Java Rockstar?

Join our newsletter to start rocking!

To get you started we give you our best selling eBooks for FREE!

 

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

 

and many more ....

 

Receive Java & Developer job alerts in your Area

I have read and agree to the terms & conditions

 

Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Inline Feedbacks
View all comments
Back to top button