Rectangle.java

class rect {

 public static void main(String args[]) {
 Rectangle r1 = new Rectangle();
 System.out.println("Area of r1: " + r1.area());
 Rectangle r2 = new Rectangle(20, 30);
 System.out.println("Area of r2: " + r2.area());
 Rectangle r3 = new Rectangle(10);
 System.out.println("Area of r3: " + r3.area());
 }

}

class Rectangle {

 int length, width;

 Rectangle() {
 this.length = 0;
 this.width = 0;
 }

 Rectangle(int length, int width) {
 this.length = length;
 this.width = width;
 }

 Rectangle(int length) {
 this.length = length;
 this.width = length;
 }

 int area() {
 return length * width;
 }

}