Unveiling Hidden Variables: A Java Application Example

In the world of Java programming, understanding variable scoping and inheritance can be a bit challenging. One common scenario is when you have a superclass and a subclass, each declaring a variable with the same name. How do you access these variables, especially when one is static and the other is an instance variable? In this blog post, we'll guide you through creating a Java application that illustrates how to access hidden variables. We'll use two classes, A and B, where class B extends A and declares an instance variable "x." By the end of this tutorial, you'll have a clear grasp of how to access and display these variables using the `display()` method in class B.

Understanding the Problem

Before we dive into the Java code, let's clarify the problem at hand:

1. Class A declares a static variable "x."
2. Class B extends A and declares an instance variable "x."
3. We want to create a method, `display()`, in class B that can display both of these variables.

Java Code Implementation

To solve this problem, we'll create a Java program with two classes, A and B, as described earlier.

class A {

    static int x = 10;

}

class B extends A {

    int x = 20;

    // Method to display both variables

    void display() {

        System.out.println("Static variable x from class A: " + A.x);

        System.out.println("Instance variable x from class B: " + this.x);

    }

}

public class VariableAccessExample {

    public static void main(String[] args) {

        B b = new B();

        b.display();

    }

}

Explanation of the Code

In the code above:

1. Class A declares a static variable `x` with a value of 10.
2. Class B extends A and declares an instance variable `x` with a value of 20.
3. Class B defines a method `display()` that displays both variables.
4. In the `main` method, we create an instance of class B and call the `display()` method to print the values of both variables.

Executing the Application

When you run the Java application, you will see the following output:

Static variable x from class A: 10

Instance variable x from class B: 20

Conclusion

In this blog post, we've created a Java application to demonstrate how to access hidden variables when a subclass declares a variable with the same name as its superclass. By extending class A and declaring an instance variable `x` in class B, we've shown how to use the `display()` method to access and display both the static and instance variables. Understanding variable scoping and inheritance is crucial in Java programming, and this example should help you clarify this concept. Feel free to experiment with the code and explore more about Java's object-oriented features. Happy coding!