关于马士兵老师的坦克大战小程序为什么用了LIST容器来装炮弹还是只能一发一发的打

Question

主窗口TankClient.java代码如下:
import java.awt.*;
import java.awt.event.*;
import java.util.List;
import java.util.ArrayList;

public class TankClient {

public static void main(String[] args) {
    new MyFrame("TankWar");
}

}

class MyFrame extends Frame {

public static final int GAME_WIDTH = 800, GAME_HEIGHT = 600;

Tank mytank = new Tank(385, 285, this);
List<Missile> ms = new ArrayList<Missile>();

Image image = null;
public MyFrame(String s) {
    super(s);
    Label l1 = new Label("r : 重置坦克位置");
    setLayout(new FlowLayout(FlowLayout.LEFT, 20, 20));
    setBackground(Color.green);
    add(l1);
    addWindowListener(new WinClose());
    addKeyListener(new KeyControl());
    this.setResizable(false);
    this.setBounds(280, 100, GAME_WIDTH, GAME_HEIGHT);
    this.setVisible(true);
    new Thread(new Repaint()).start();
}

public void paint(Graphics g) {
    g.drawString("missile :" + ms.size(), 20, 550);
    for(int i = 0;i < ms.size();i++) {
        Missile m1 = ms.get(i);
        if(!m1.islive()) ms.remove(m1);
        m1.draw(g);
    }
    mytank.draw(g);
}

public void update(Graphics g) {
    if (image == null) {
        image = this.createImage(GAME_WIDTH, GAME_HEIGHT);
    }
    Graphics g11 = image.getGraphics();
    Color c = g11.getColor();
    g11.setColor(Color.green);
    g11.fillRect(0, 0, GAME_WIDTH, GAME_HEIGHT);
    g11.setColor(c);
    this.paint(g11);
    g.drawImage(image, 0, 0, null);
}

/*
 * public boolean isResizable() { return false; }
 */

private class Repaint implements Runnable {
    public void run() {
        while (true) {
            repaint();
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

private class WinClose extends WindowAdapter {
    public void windowClosing(WindowEvent e) {
        setVisible(false);
        System.exit(0);
    }

}

private class KeyControl extends KeyAdapter {
    public void keyPressed(KeyEvent e) {
        mytank.key(e);
    }

    public void keyReleased(KeyEvent e) {
        mytank.keyrelease(e);
    }

}

}

坦克这个类的代码如下 Tank.java :

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;

public class Tank {
public int x, y;
public final int XTANK_SPEED = 5, YTANK_SPEED = 5, WIDTH = 30,
HEIGHT = 30;
private final Color MYTANKCOLOR = Color.blue;

enum Direction {
    L, LU, U, RU, R, RD, D, LD, S
};

Direction dir = Direction.S;
static Direction ptDir = Direction.U;
private boolean bl = false, br = false, bu = false, bd = false;
MyFrame mf;

public Tank(int x, int y) {
    this.x = x;
    this.y = y;
}

public Tank(int x, int y, MyFrame mf) {
    this(x, y);
    this.mf = mf;
}

public void reset() {
    x = 380;
    y = 280;
}

public void draw(Graphics g) {
    Color c = g.getColor();
    g.setColor(MYTANKCOLOR);
    g.fillOval(x, y, WIDTH, HEIGHT);
    g.setColor(c);
    move();

    switch (ptDir) {
    case L:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x, y + HEIGHT / 2);
        g.drawLine(x, y , x +  WIDTH, y);
        g.drawLine(x, y + HEIGHT , x +  WIDTH, y + HEIGHT);
        break;
    case LU:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x, y);
        break;
    case U:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x + WIDTH / 2, y);
        g.drawLine(x, y, x, y + HEIGHT);
        g.drawLine(x + WIDTH, y , x +  WIDTH, y + HEIGHT);
        break;
    case RU:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x + WIDTH, y);
        break;
    case R:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x + WIDTH, y + HEIGHT / 2);
        g.drawLine(x, y , x +  WIDTH, y);
        g.drawLine(x, y + HEIGHT , x +  WIDTH, y + HEIGHT);
        break;
    case RD:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x + WIDTH, y + HEIGHT);
        break;
    case D:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x + WIDTH / 2, y + HEIGHT);
        g.drawLine(x, y, x, y + HEIGHT);
        g.drawLine(x + WIDTH, y , x +  WIDTH, y + HEIGHT);
        break;
    case LD:
        g.drawLine(x + WIDTH / 2, y + HEIGHT / 2, x, y + HEIGHT);
        break;

    }

}

public void key(KeyEvent e) {
    int k = e.getKeyCode();
    switch (k) {
    case KeyEvent.VK_UP:
        bu = true;
        break;
    case KeyEvent.VK_DOWN:
        bd = true;
        break;
    case KeyEvent.VK_LEFT:
        bl = true;
        break;
    case KeyEvent.VK_RIGHT:
        br = true;
        break;
    case KeyEvent.VK_R:
        reset();
        break;

    }
    locate();
}

public void keyrelease(KeyEvent e) {
    int k = e.getKeyCode();
    switch (k) {
    case KeyEvent.VK_UP:
        bu = false;
        break;
    case KeyEvent.VK_DOWN:
        bd = false;
        break;
    case KeyEvent.VK_LEFT:
        bl = false;
        break;
    case KeyEvent.VK_RIGHT:
        br = false;
        break;
    case KeyEvent.VK_Z:
        fire();
        break;
    }
    locate();
}

public void locate() {
    if (!bu && !bd && bl && !br)
        dir = Direction.L;
    else if (bu && !bd && bl && !br)
        dir = Direction.LU;
    else if (bu && !bd && !bl && !br)
        dir = Direction.U;
    else if (bu && !bd && !bl && br)
        dir = Direction.RU;
    else if (!bu && !bd && !bl && br)
        dir = Direction.R;
    else if (!bu && bd && !bl && br)
        dir = Direction.RD;
    else if (!bu && bd && !bl && !br)
        dir = Direction.D;
    else if (!bu && bd && bl && !br)
        dir = Direction.LD;
    else if (!bu && !bd && !bl && !br)
        dir = Direction.S;
}

public void move() {
    switch (dir) {
    case L:
        x -= XTANK_SPEED;
        break;
    case LU:
        x -= XTANK_SPEED;
        y -= YTANK_SPEED;
        break;
    case U:
        y -= YTANK_SPEED;
        break;
    case RU:
        x += XTANK_SPEED;
        y -= YTANK_SPEED;
        break;
    case R:
        x += XTANK_SPEED;
        break;
    case RD:
        x += XTANK_SPEED;
        y += YTANK_SPEED;
        break;
    case D:
        y += XTANK_SPEED;
        break;
    case LD:
        x -= XTANK_SPEED;
        y += YTANK_SPEED;
        break;
    }

    if (this.dir != Direction.S) {
        this.ptDir = this.dir;
    }

}

public Missile fire() {
    Missile m = new Missile(x + WIDTH / 2 - Missile.w / 2, y + HEIGHT / 2- Missile.h / 2, ptDir);
    mf.ms.add(m);   
    return m;
}

public static void main(String[] args) {

}

}

炮弹类代码如下
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;

public class Missile {
static int x,y;
static Tank.Direction dir;
static int X_SPEED = 1,Y_SPEED = 1,w = 10, h = 10;
private boolean islive = true;

public boolean islive() {
    return islive;
}


static MyFrame mf1;

public Missile(int x,int y,Tank.Direction dir) {
     this.x = x;
     this.y = y;
     this.dir = dir;
}

public Missile(int x,int y,Tank.Direction dir,MyFrame mf1) {
    this(x,y,dir);
    this.mf1 = mf1;
}

public void draw(Graphics g) {
   Color c = g.getColor();
   g.setColor(Color.RED);
   g.fillOval(x, y,w , h);
   g.setColor(c);

   move();
}

private  void move() {
    switch(dir) {
    case L:
        x -= X_SPEED;
        break;
    case LU:
        x -= X_SPEED;
        y -= Y_SPEED;
        break;
    case U:
        y -= Y_SPEED;
        break;
    case RU:
        x += X_SPEED;
        y -= Y_SPEED;
        break;
    case R:
        x += X_SPEED;
        break;
    case RD:
        x += X_SPEED;
        y += Y_SPEED;
        break;
    case D:
        y += X_SPEED;
        break;
    case LD:
        x -= X_SPEED;
        y += Y_SPEED;
        break;  
    }

    if(x < 0 || y < 0 || x > MyFrame.GAME_WIDTH || y > MyFrame.GAME_HEIGHT) {
        islive = false;
    }
}

public static void main(String[] args) {

}

public String toString() {
    return ("x: " + x + "y: " + y + "dir:" + dir);
}

}

Answer 1

public class Missile {
int x,y;
Tank.Direction dir;
int X_SPEED = 1,Y_SPEED = 1,w = 10, h = 10;
private boolean islive = true;
把Missile对象中的变量改成非静态的