what is constructor overloading in java? Explain it with suitable program

Constructor overloading in Java is a technique of having more than one constructor with different parameter lists. They are arranged in a way that each constructor performs a different task. They are differentiated by the compiler by the number of parameters in the list and their types.

Here is a simple example of constructor overloading in Java:

class Rectangle {
    // instance variables
    private int length;
    private int breadth;

    // Constructor with no parameter
    Rectangle() {
        length = 5;
        breadth = 2;
    }

    // Constructor with two parameters
    Rectangle(int l, int b) {
        length = l;
        breadth = b;
    }

    // Method to calculate area
    public int getArea() {
        return length * breadth;
    }

    public static void main(String args[]) {
        // Creating objects
        Rectangle rect1 = new Rectangle();
        Rectangle rect2 = new Rectangle(4, 6);

        // Displaying area of rectangles
        System.out.println("Area of rect1: " + rect1.getArea());
        System.out.println("Area of rect2: " + rect2.getArea());
    }
}

In the above program, we have two constructors: one without any parameters and one with two parameters. When we create an object rect1 using the no-argument constructor, the default values are used. When we create another object rect2 using the parameterized constructor, the values provided are used. This is a simple example of constructor overloading in Java.