Constructor Overloading in Java

// Creating a class
class Rectangle
{
    int length, breadth;
   
    // Default constructor
    Rectangle()
    {
        length = 0;
        breadth = 0;
    }
   
    // Parameterised constructor
    // Containing only length
    Rectangle(int length)
    {
        this.length = length;
        breadth = 1;
    }

    // Parameterised constructor
    // Containing length and breadth both
    Rectangle(int length, int breadth)
    {
        this.length = length;
        this.breadth = breadth;
    }
   
    // Print the area of the rectangle
    void area()
    {
        System.out.println(length * breadth);
    }
   
}

class HelloWorld {
    public static void main(String[] args) {
       
        // Creating an object
        // by calling default constructor
        Rectangle rect1 = new Rectangle();
        rect1.area();
       
       
        // Creating an object
        // by calling constructor having only length
        // as argument
        Rectangle rect2 = new Rectangle(10);
        rect2.area();
       
        // Creating an object
        // by calling constructor having both length
        // and breadth as argument
        Rectangle rect3 = new Rectangle(10, 20);
        rect3.area();
    }
}

// Creating a class
class Rectangle
{
    int length, breadth;
   
    // Default constructor
    Rectangle()
    {
        length = 0;
        breadth = 0;
    }
   
    // Parameterised constructor
    // Containing only length
    Rectangle(int length)
    {
        this.length = length;
        breadth = 1;
    }

    // Parameterised constructor
    // Containing length and breadth both
    // But here this() reference is given
    Rectangle(int length, int breadth)
    {
        this();
    }
   
    // Print the area of the rectangle
    void area()
    {
        System.out.println(length * breadth);
    }
   
}

class HelloWorld {
    public static void main(String[] args) {
       
        // Creating an object
        // by calling default constructor
        Rectangle rect1 = new Rectangle();
        rect1.area();
       
       
        // Creating an object
        // by calling constructor having only length
        // as argument
        Rectangle rect2 = new Rectangle(10);
        rect2.area();
       
        // Creating an object
        // by calling constructor having both length
        // and breadth as argument
        Rectangle rect3 = new Rectangle(10, 20);
        rect3.area();
    }
}