Variables in Java Do Not Follow Polymorphism and Overriding

Last Updated : 23 Sep, 2021

Variables in Java do not follow polymorphism. Overriding is only applicable to methods but not to variables. In Java, if the child and parent class both have a variable with the same name, Child class's variable hides the parent class's variable, even if their types are different. This concept is known as Variable Hiding. In the case of method overriding, overriding methods completely replace the inherited methods but in variable hiding, the child class hides the inherited variables instead of replacing them which basically means that the object of Child class contains both variables but Child's variable hides Parent's variable.

Hence when we try to access the variable within Child class, it will be accessed from the child class. If we are trying to access the variable outside of the Parent and Child class, then the instance variable is chosen from the reference type.

Example

Java

// Java Program Illustrating Instance variables
// Can not be Overridden

// Class 1
// Parent class
// Helper class
class Parent {
    // Declaring instance variable by name `a`
    int a = 10;
    public void print()
    {
        System.out.println("inside B superclass");
    }
}

// Class 2
// Child class
// Helper class
class Child extends Parent {

    // Hiding Parent class's variable `a` by defining a
    // variable in child class with same name.
    int a = 20;

    // Method defined inside child class
    public void print()
    {
        // Print statement
        System.out.println("inside C subclass");
    }
}

// Main class
public class GFG {

    // Main driver method
    public static void main(String[] args)
    {
        // Creating a Parent class object
        // Reference Parent
        Parent obj = new Child();

        // Calling print() method over object created
        obj.print();

        // Printing superclass variable value 10
        System.out.println(obj.a);

        // Creating a Child class object
        // Reference Child
        Child obj2 = new Child();

        // Printing childclass variable value 20
        System.out.println(obj2.a);
    }
}

Output

inside C subclass
10
20

Conclusion:

Variables in Java do not follow polymorphism and overriding. If we are trying to access the variable outside of Parent and Child class, then the instance variable is chosen from the reference type.