Overriding member variables in Java (Variable Hiding)

Overriding member variables in Java (Variable Hiding)

In Java, you can override methods in subclasses to provide specific implementations, but you cannot override member variables (fields) in the same way. What happens with member variables is known as "variable hiding" rather than "variable overriding."

Here's what you need to know about variable hiding in Java:

  1. Inheritance and Member Variables:

    • When a subclass declares a field with the same name as a field in its superclass, it effectively hides the field in the superclass.
    • This means that the subclass has its own separate field with the same name, and it does not override the field in the superclass.
    • The two fields (one in the superclass and one in the subclass) can have different values and are distinct.

  2. Access to Hidden Variables:

    • To access the hidden field from the superclass, you can use the super keyword.
    • To access the hidden field from the subclass, you can use the field name directly.

Here's an example to illustrate variable hiding:

class Animal { int legs = 4; void displayInfo() { System.out.println("Animal has " + legs + " legs."); } } class Bird extends Animal { int legs = 2; @Override void displayInfo() { System.out.println("Bird has " + legs + " legs."); System.out.println("Animal has " + super.legs + " legs."); } } public class Main { public static void main(String[] args) { Bird bird = new Bird(); bird.displayInfo(); } }

In this example, we have a superclass Animal with a member variable legs set to 4. The subclass Bird also has a member variable legs, but it's set to 2. The displayInfo method in the Bird class overrides the same method in the Animal class and displays the values of both legs variables.

When we create an instance of Bird and call bird.displayInfo(), the output will be:

Bird has 2 legs. Animal has 4 legs.

As you can see, the subclass Bird hides the legs variable from the superclass Animal, and we can access both variables using the legs field directly in the subclass and using super.legs to access the one from the superclass.

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