// This class is an example using points
public class PointClient {

    public static void main(String[] args) {
        Point p = new Point(1, 2);
        System.out.println("main:    Before        = " + p);
        change1(p);
        System.out.println("main:    After change1 = " + p);

        change2(p);
        System.out.println("main:    After change2 = " + p);

        // approach 2 doesn't work, need x=change(x) pattern
        p = change3(p);
        System.out.println("main:    After change3 = " + p);
    }

    public static void change1(Point p) {
        System.out.println("change1: Before        = " + p);
        p.x = 14;
        System.out.println("change1: After         = " + p);
    }

    public static void change2(Point p) {
        System.out.println("change2: Before        = " + p);
        p = new Point(7, 8);
        System.out.println("change2: After         = " + p);
    }

    public static Point change2(Point p) {
        System.out.println("change3: Before        = " + p);
        p = new Point(7, 8);
        System.out.println("change3: After         = " + p);
        return p;
    }
}