子弹超出界面删除子弹对象
实现思路:
通过循环遍历获取子弹,调用子弹销毁方法.
如果子弹的x坐标小于0或者大于界面宽度删除子弹对象.
如果子弹的y坐标小于0或者大于界面高度删除子弹对象.
代码实现:
1、设置类循环遍历子弹
1 package Itheima;
2
3 import java.util.List;
4 import java.util.concurrent.CopyOnWriteArrayList;
5
6 import org.itheima.game.Window;
7 import org.lwjgl.input.Keyboard;
8
9 import Itheima.bean.Bullet;
10 import Itheima.bean.Direction;
11 import Itheima.bean.Element;
12 import Itheima.bean.Tank;
13 import Itheima.bean.Wall;
14
15 public class TankWorld extends Window {
16 Tank tank;
17 Wall wall;
18 List<Element> list;
19
20 public TankWorld(String title, int width, int height, int fps) {
21 super(title, width, height, fps);
22 // TODO 自动生成的构造函数存根
23 }
24
25 @Override
26 protected void onCreate() {
27 list = new CopyOnWriteArrayList<>();
28 tank = new Tank(0, 0);
29 wall = new Wall(64, 64);
30 list.add(tank);
31 list.add(wall);
32 }
33
34 @Override
35 protected void onMouseEvent(int key, int x, int y) {
36 // TODO 自动生成的方法存根
37
38 }
39
40 @Override
41 protected void onKeyEvent(int key) {
42 switch (key) {
43 case Keyboard.KEY_UP:
44 tank.move(Direction.UP);
45 break;
46
47 case Keyboard.KEY_DOWN:
48 tank.move(Direction.DOWN);
49 break;
50 case Keyboard.KEY_LEFT:
51 tank.move(Direction.LEFT);
52 break;
53 case Keyboard.KEY_RIGHT:
54 tank.move(Direction.RIGHT);
55 break;
56 case Keyboard.KEY_SPACE:
57 Bullet bullet = tank.fire();
58 list.add(bullet);
59 break;
60 }
61 }
62
63 @Override
64 protected void onDisplayUpdate() {
65 for (Element e : list) {
66 e.draw();
67 System.out.println(list.size());
68 }
69
70
71 for (Element e1 : list) {
72 if(e1 instanceof Tank){ //遍历到Tank对象
73 Tank t = (Tank) e1; //将e1转换成Tank类
74 for (Element e2 : list) {
75 if(e2 instanceof Wall){ //遍历到Wall对象
76 Wall w = (Wall) e2; //将e2转换成Wall对象
77 boolean result = t.impact(w); //判断Tank与Wall是否发生碰撞
78 if(result){
79 break; //如果撞上了就跳出循环 不继续和下一个墙做判断
80 }
81 }
82 }
83 }
84 }
85
86 for (Element e1 : list) {
87 if(e1 instanceof Bullet){ //如果e1是子弹
88 Bullet b = (Bullet) e1; //将e1转换成子弹对象
89 boolean result = b.isDestroy(); //调用子弹销毁方法
90 if(result){
91 list.remove(b); //从集合删除子弹对象
92 }
93 }
94 }
95 }
96
97 }
2、子弹类销毁方法
1 package Itheima.bean;
2
3 import java.io.IOException;
4
5 import org.itheima.game.utils.DrawUtils;
6
7 import Itheima.Constants;
8
9 public class Bullet extends Element {
10 Direction dir;
11 private int speed = 32; //子弹速度
12 public Bullet(Tank tank) {
13 int x1 = tank.x;
14 int y1 = tank.y;
15 int w1 = tank.width;
16 int h1 = tank.height;
17 this.dir = tank.dir;
18 switch (dir) { //根据tank的方向计算子弹坐标
19 case UP:
20 this.imagePath = "res/img/bullet_u.gif";
21 getSize();
22 this.x = x1 + (w1 - this.width) / 2;
23 this.y = y1 - this.height;
24 break;
25
26 case DOWN:
27 this.imagePath = "res/img/bullet_d.gif";
28 getSize();
29 this.x = x1 + (w1 - this.width) / 2;
30 this.y = y1 + w1;
31 break;
32 case LEFT:
33 this.imagePath = "res/img/bullet_l.gif";
34 getSize();
35 this.x = x1 - this.width;
36 this.y = y1 + (h1 - this.height) / 2;
37 break;
38 case RIGHT:
39 this.imagePath = "res/img/bullet_r.gif";
40 getSize();
41 this.x = x1 + w1;
42 this.y = y1 + (h1 - this.height) / 2;
43 break;
44 }
45 }
46
47 public void draw() { //重写draw方法
48 try {
49 DrawUtils.draw(imagePath, x, y);
50 } catch (IOException e) {
51 // TODO 自动生成的 catch 块
52 e.printStackTrace();
53 }
54 switch (dir) {
55 case UP:
56 y -= speed;
57 break;
58
59 case DOWN:
60 y += speed;
61 break;
62 case LEFT:
63 x -= speed;
64 break;
65 case RIGHT:
66 x += speed;
67 break;
68 }
69 }
70
71 public boolean isDestroy() { //子弹销毁方法
72 if(x<0 || x>Constants.WIDTH || y<0 || y>Constants.HEIGHT){
73 return true;
74 }
75 return false;
76 }
77 }
随笔说:
如果不进行删除无效的对象，运行时间越长，则游戏数据会越来越大。
所以还是有必要优化一下的。
