Odtnhj

I am working through a java exercise and am somewhat confused what the new values of the last 4 lines of code are.

public class Snake 
 public Snake x = null;
 public Snake y = null;

 public static void main(String args) 
 Snake a = new Snake();
 Snake b = new Snake();
 a.x = a;
 b.x = a.x;
 b.y = b.x;
 a.y = b.y.x;
 

Then you understood that a and b are two snakes. But they are really references to two different snakes.

a.x = a : means make a.x refer to snake referred by a.

b.x = a.x : means make b.x refer to snake referred by a.x (so the same as a).

b.y = b.x : means make b.y refer to snake referred by b.x (so the same as a).

a.y = b.y.x: means make a.y refer to snake referred by b.y.x, as b.y refers to a, this refers to a.x which is the same as a.

This is how it works:

a.x = a;

the x Snake object (property) of the a Snake object becomes a reference (points) to the a Snake object itself.

b.x = a.x;

the x Snake object (property) of the b Snake object becomes a reference (points) to the a.x Snake object which previously was set to refer to the a Snake object.
So this b.x also becomes a reference (points) to the a Snake object .

b.y = b.x;

the y Snake object (property) of the b Snake object becomes a reference (points) to the b.x Snake object which previously was set to refer to the a Snake object.
So this b.y also becomes a reference (points) to the a Snake object .

a.y = b.y.x;

the y Snake object (property) of the a Snake object becomes a reference (points) to the b.y.x Snake object and since b.y was previously set to a it is equivalent to a.x which previously was set to refer to the a Snake object.
So this a.y also becomes a reference (points) to the a Snake object .


Finally: all the left parts of the assignments refer (point) to a.