在数据结构中存储对象

 1 import java.awt.*;
 2 import java.util.*;
 3 
 4 
 5 public class Battlepoint {
 6     ArrayList<Point> targets = new ArrayList<Point>();
 7     
 8     public Battlepoint() {
 9         //create targets to shoot at
10         createTargets();
11         //display the game map
12         showMap();
13         //shoot at three points
14         shoot(7, 4);
15         shoot(3, 3);
16         shoot(9, 2);
17         //display the map again
18         showMap();
19     }
20     
21     private void showMap() {
22         System.out.println("\n   1  2  3  4  5  6  7  8  9");
23         for (int column = 1; column < 10; column++) {
24             for (int row = 1; row < 10; row++) {
25                 if (row == 1) {
26                     System.out.print(column + " ");
27                 } 
28                 System.out.print(" ");
29                 Point cell = new Point(row, column);
30                 if (targets.indexOf(cell) > -1) {
31                     //a target is at this position
32                     System.out.print("X");
33                 } else {
34                     //no target is here
35                     System.out.print(".");
36                 }
37                 System.out.print(" ");
38             }
39             System.out.println();
40         }
41         System.out.println();
42     }
43     
44     private void createTargets() {
45         Point p1 = new Point(5, 9);
46         targets.add(p1);
47         Point p2 = new Point(4, 5);
48         targets.add(p2);
49         Point p3 = new Point(9, 2);
50         targets.add(p3);
51     }
52     
53     private void shoot(int x, int y) {
54         Point shot = new Point(x, y);
55         System.out.print("Firing at (" + x + "," + y + ")...");
56         if (targets.indexOf(shot) > -1) {
57             System.out.println("you sank my battlepoint!");
58             targets.remove(shot);
59         } else {
60             System.out.println("miss.");
61         }
62     }
63     
64     public static void main(String[] arguments) {
65         new Battlepoint();
66     }
67 }