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Learn how to invoke parent class methods from child class objects in Java. We'll break down the problem and provide a simple solution with code examples.
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This video is based on the question https://stackoverflow.com/q/73820618/ asked by the user 'Aman Malakar' ( https://stackoverflow.com/u/7349335/ ) and on the answer https://stackoverflow.com/a/73820686/ provided by the user 'SpaceTrucker' ( https://stackoverflow.com/u/1466267/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Can You Invoke a Parent Class Method from a Child Class Object in Java?

In Java, inheritance allows a child class to inherit properties and methods from a parent class. A common question arises: is it possible to invoke a parent class method through a child class object? This topic can be a bit tricky if you're not familiar with how Java handles method overriding and object references. In this guide, we will explore this problem and provide a clear solution.

The Problem at Hand

Imagine you have a parent class called Human and a child class Aman that extends Human. You may override a method in Aman, but occasionally you need to call the original method in Human. The fundamental concern is whether you can call a parent class method using a child class object. For example, take a look at the following Java code:

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When the main program tries to execute obj.super.getAge(), it results in a compilation error. But how can you get it to print "Human's age is 21"?

Understanding the Solution

Why obj.super.getAge() Doesn't Work

The super keyword is designed to refer to the parent class from within the subclass. Hence, trying to access super from outside the subclass (as in obj.super.getAge()) violates Java’s principles of encapsulation and results in an error.

The Right Way to Call Parent Class Methods

To invoke a method from a parent class, you need to do so within the child class itself. Here's how you can achieve that by adding a method in the Aman class to retrieve the parent class age:

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Putting It All Together

Now, modify the main function in the Main class like this:

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Summary of Steps

Create a method in the child class: Introduce a new method in your child class (e.g., getHumanAge()) that calls the desired parent class method using super.

Access through the child class object: Call this new method instead of trying to directly access the parent’s method from outside of its class.

Conclusion

By using the super keyword properly within your child class, you can easily access methods from the parent class. While Java restricts direct access to maintain encapsulation and code integrity, the design encourages developers to manage interactions between classes in a structured manner.

Now you can confidently invoke a parent class method from a child class object in Java without any complications! Happy coding!