Variable in subclass hides the variable in the super class in Java

Sometimes the variable in the subclass may hide the variable in the super class. In that case, the parent class variable can be referred to using the super keyword in Java.

A program that demonstrates this is given as follows:

Example

 Live Demo

class A {
   char ch;
}
class B extends A {
   char ch;
   B(char val1, char val2) {
      super.ch = val1;
      ch = val2;
   }
   void display() {
      System.out.println("In Superclass, ch = " + super.ch);
      System.out.println("In subclass, ch = " + ch);
   }
}
public class Demo {
   public static void main(String args[]) {
      B obj = new B('B', 'E');
      obj.display();
   }
}

Output

In Superclass, ch = B
In subclass, ch = E

Now let us understand the above program.

The class A contains a data member ch. The class B uses the extends keyword to derive from class A. It also contains a data member ch and constructor B().

The ch variable in the subclass(B) hides the ch variable in the super class(A). So the parent class variable ch is referred to using the super keyword in constructor B(). The method display() in class B prints the values of ch in subclass and superclass. A code snippet which demonstrates this is as follows:

class A {
   char ch;
}
class B extends A {
   char ch;
   B(char val1, char val2) {
      super.ch = val1;
      ch = val2;
   }
   void display() {
      System.out.println("In Superclass, ch = " + super.ch);
      System.out.println("In subclass, ch = " + ch);
   }
}

In the main() method in class Demo, an object obj of class B is created. Then the method display() is called. A code snippet which demonstrates this is as follows:

public class Demo {
   public static void main(String args[]) {
      B obj = new B('B', 'E');
      obj.display();
   }
}

Vikyath Ram

Published on 15-Feb-2019 11:47:41