Which Rectangle constructor does instance box2 call? Why? What concept does this demonstrate?

Which Rectangle constructor does instance box2 call? Why? What concept does this demonstrate?

Rectangle.java

public class Rectangle

{

public int length;

public int width;

public Rectangle(int l, int w)

{

length = l;

width = w;

}

public Rectangle(int l)

{

this(l, 10);

}

public Rectangle(Rectangle other)

{

this(other.length, other.width);

}

}

Test2.java

public class Test2

{

static int a;

public static void main(String[] args)

{

Rectangle box1 = new Rectangle(10,10);

Rectangle box2 = new Rectangle(box1);

Rectangle box3 = new Rectangle(10);

Rectangle box4 = box1;

box1 = null;

System.out.println("box(l,w) = (" + box2.length + "," + box2.width + ")");

System.out.println("box(l,w) = (" + box3.length + "," + box3.width + ")");

System.out.println("box(l,w) = (" + box4.length + "," + box4.width + ")");

System.out.println("All of the above produce the same output!!!");

box2 = null;

System.out.println("n");

a = 1;

System.out.println("a = " + a);

int a;

a = 101;

System.out.println("a = " + a);

System.out.println("a = " + Test2.a);

}

}