Using "this" keyword in Constructors

package thisss;

public class Triangle{
    double x,y;
    Triangle(){
        this(0,0);
    }
    Triangle(double x){
        this(x,x);
    }
    Triangle(double x, double y){
        this.x=x;
        this.y=y;
    }
    void area(){
        System.out.println("The area of the triangle is: " + (x*y)/2.0);
    }
}


package thisss;

public class Main{
    public static void main(String args[]){
        Triangle t = new Triangle();
        Triangle tri = new Triangle(3);
        Triangle tri2 = new Triangle(3,2);
        t.area();
        tri.area();
        tri2.area();
     }
}