Question

在写韩顺平坦克大战的时候出现了问题，坦克无法移动，下面是代码！

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

import javax.swing.JFrame;
import javax.swing.JPanel;

import com.sun.java_cup.internal.internal_error;

public class MyTankWar extends JFrame {
MyTankWar() {

add(new Mypanel());
addKeyListener(new Mypanel());
setSize(400, 300);
setLocation(300, 150);
setVisible(true);
}

public static void main(String[] args) {
MyTankWar mtw = new MyTankWar();
}
}

class Mypanel extends JPanel implements KeyListener {

Tank tank = new Tank(100,100);

public void paint(Graphics g) {

g.fillRect(0, 0, 400, 300);
tank.draw(tank.getX(), tank.getY(), g, tank.getDirect(), 0);
}

public void keyPressed(KeyEvent e) {

tank.move(e);
this.repaint();
}

public void keyReleased(KeyEvent e) {

}
public void keyTyped(KeyEvent e) {
}
}
class Tank {
int x,y;

int direct=0;

public Tank(int x, int y) {
this.x = x;
this.y = y;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public void draw(int x, int y, Graphics g, int direct, int type) {

switch (type) {
case 0:
g.setColor(Color.CYAN);
break;
case 1:
g.setColor(Color.YELLOW);
break;
default:
break;
}

switch (direct) {
case 0:
g.fill3DRect(x, y, 5, 30, false);
g.fill3DRect(x + 15, y, 5, 30, false);
g.fill3DRect(x + 5, y + 5, 10, 20, false);
g.fillOval(x + 5, y + 10, 10, 10);
g.drawLine(x + 10, y + 15, x + 10, y);
break;

default:
break;
}
}

void move(KeyEvent e) {
int key = e.getKeyCode();
switch (key) {
case KeyEvent.VK_DOWN:
y=y+5;
break;
case KeyEvent.VK_LEFT:
x--;
break;
case KeyEvent.VK_RIGHT:
x++;
break;
case KeyEvent.VK_UP:
y--;
break;
default:
break;
}
}

public int getDirect() {
return direct;
}

public void setDirect(int direct) {
this.direct = direct;
}

}

可能有点长 这个问题搞了我几天了，头好晕，请帮帮忙，我dbug调试是我修改了x和y的值在repainl的时候没有改边painl的值。难道真的不能改变吗，按照Java的语法，是可以改变的啊，我没有按照韩顺平老师的写法写，按照自己的思维来写的！跪求高手解答
我发现问题在哪了 repaint在业没有执行过paint了

Answer 1

同学
add(new Mypanel());
addKeyListener(new Mypanel());
你这样弄是两个新的Mypanel 不是同一个
要用
Mypanel mypanel=newMypanel();
this.add(mypanel);
this.addKeyListener(mypanel);