What is the purpose of the super() keyword in Java?

The super() keyword is used in object-oriented programming to refer to the immediate parent class of the current object. Here are the steps to understand its purpose:

1. Access Parent Class Constructor: The primary use of super() is to call the constructor of the parent class. This is particularly useful when the parent class has a parameterized constructor, and you need to initialize the parent class's fields from the child class.

2. Invoke Parent Class Methods: super can also be used to call methods defined in the parent class that have been overridden in the child class. This allows the child class to use the parent class's implementation of a method.

3. Access Parent Class Fields: If a field is hidden by a field of the same name in the child class, super can be used to access the hidden field in the parent class.

Here is an example to illustrate these points:

class Parent {
    int x;

    Parent(int x) {
        this.x = x;
    }

    void display() {
        System.out.println("Parent x: " + x);
    }
}

class Child extends Parent {
    int x;

    Child(int x1, int x2) {
        super(x1); // Calls the constructor of Parent class
        this.x = x2;
    }

    void display() {
        super.display(); // Calls the display method of Parent class
        System.out.println("Child x: " + x);
    }
}

public class Main {
    public static void main(String[] args) {
        Child child = new Child(10, 20);
        child.display();
    }
}

In this example:

• super(x1) calls the constructor of the Parent class.
• super.display() calls the display method of the Parent class.
• super.x (if used) would access the x field of the Parent class.