/*
Java 2, v5.0 (Tiger) New Features
by Herbert Schildt
ISBN: 0072258543
Publisher: McGraw-Hill/Osborne, 2004
*/
// Two-dimensional coordinates.
class TwoD {
  int x, y;
  TwoD(int a, int b) {
    x = a;
    y = b;
  }
}
// Three-dimensional coordinates.
class ThreeD extends TwoD {
  int z;
  ThreeD(int a, int b, int c) {
    super(a, b);
    z = c;
  }
}
// Four-dimensional coordinates.
class FourD extends ThreeD {
  int t;
  FourD(int a, int b, int c, int d) {
    super(a, b, c);
    t = d;
  }
}
// This class holds an array of coordinate objects.
class Coords<T extends TwoD> {
  T[] coords;
  Coords(T[] o) { coords = o; }
}

// Demonstrate a bounded wildcard.
public class BoundedWildcard {

  static void showXY(Coords<? extends TwoD> c) {
    System.out.println("X Y Coordinates:");
    for(int i=0; i < c.coords.length; i++) {
      System.out.println(c.coords[i].x + " " + c.coords[i].y);
    }
    System.out.println();
  }

  static void showXYZ(Coords<? extends ThreeD> c) {
    System.out.println("X Y Z Coordinates:");
    for(int i=0; i < c.coords.length; i++)
      System.out.println(c.coords[i].x + " " +
                         c.coords[i].y + " " +
                         c.coords[i].z);
    System.out.println();
  }

  static void showAll(Coords<? extends FourD> c) {
    System.out.println("X Y Z T Coordinates:");
    for(int i=0; i < c.coords.length; i++)
      System.out.println(c.coords[i].x + " " +
                         c.coords[i].y + " " +
                         c.coords[i].z + " " +
                         c.coords[i].t);
    System.out.println();
  }

  public static void main(String args[]) {
    TwoD td[] = {
      new TwoD(0, 0),
      new TwoD(7, 9),
      new TwoD(18, 4),
      new TwoD(-1, -23)
    };
    Coords<TwoD> tdlocs = new Coords<TwoD>(td);
    System.out.println("Contents of tdlocs.");
    showXY(tdlocs); // OK, is a TwoD
//  showXYZ(tdlocs); // Error, not a ThreeD
//  showAll(tdlocs); // Erorr, not a FourD
    // Now, create some FourD objects.
    FourD fd[] = {
      new FourD(1, 2, 3, 4),
      new FourD(6, 8, 14, 8),
      new FourD(22, 9, 4, 9),
      new FourD(3, -2, -23, 17)
    };
    Coords<FourD> fdlocs = new Coords<FourD>(fd);
    System.out.println("Contents of fdlocs.");
    // These are all OK.
    showXY(fdlocs);
    showXYZ(fdlocs);
    showAll(fdlocs);
  }
}