// Jeremy Lipschutz
// Short program highlighting how object variables
// use reference semantics

public class ReferenceSemantics {

   public static void main(String[] args) {

      Point p1 = new Point(1,2);
      Point p2 = p1;
      Point p3 = new Point(p1.x, p1.y);      
      
      System.out.println(p1);
      System.out.println(p2);
      System.out.println(p3);
      
      
      // Note here that because p1 and p2 both "refer" to the same object,
      // we see that both of them have the same x and y fields, 25 and 67.
      p1.x = 25;
      p2.y = 67;
      p3.x = 20;
      
      System.out.println(p1);
      System.out.println(p2);
      System.out.println(p3);
      
      // creates an array with null elements
      Point[] points = new Point[5];
      for(int i = 0; i < points.length; i++) {
         points[i] = new Point(i * 2, i * 2 + 1);
      }
      
      /*
      // This is the standard way of looping through the array and printing out all
      // the values
      for(int i = 0; i < points.length; i++) {
         System.out.println(points[i]);
      }
      */
      
      // Here we are using the "for-each" loop. Each iteration of the loop,
      // The variable "p" will be set to a different Point in the data structure
      // "points" you are looping over. You cannot decide the order in which the
      // points are visited, but it is quite nice when you just want to print all of
      // them!
      for(Point p : points) {
         System.out.println(p);
      }
   }
}