请高手帮帮忙，Java多线程与图形界面的问题

麻烦高手帮忙看一下，为什么按空格后炮弹不发射了，再按空格炮弹还不发射。（我想的是按空格炮弹发射，再按不发射；按一下发射一次也行）；小弟菜鸟，初学Java。import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Random;
import java.lang.Math;
public class Pete extends JFrame
{
public enemytank enemy;
public enemytank1 enemy1;
public ammo ammo1;
public ammoo ammoo1;
public myammoo myammoo1;
public int i=0;
    PetePanel pete = new PetePanel();
public Pete() 
{
super("Tank Battle");
        setSize(512, 430);
setResizable(false);
enemy=new enemytank(pete);
enemy1=new enemytank1(pete);
ammo1=new ammo(pete);
ammoo1=new ammoo(pete);
myammoo1=new myammoo(pete);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//添加窗口关闭
        JPanel pane = new JPanel();
        pane.setLayout(new GridLayout(1, 1, 15, 15));
        pane.add(pete);
        this.addKeyListener(new KeyAdapter(){//得到焦点，放frame容易获取焦点。
            @Override
            public void keyPressed(KeyEvent e)
{
                System.out.println("ppppp");
if (e.getKeyCode() == KeyEvent.VK_SPACE) //fire
{
i=i+1;
if(i%2==0)
                    pete.live=1;
else pete.live=0;
System.out.println(pete.live);
                }
            }            public void keyTyped(KeyEvent e)
{
                System.out.println("kkkkk");
            }            public void keyReleased(KeyEvent e) 
{
                System.out.println("rrrrrr");
            }
        });
        setContentPane(pane);//建立联系与pane
enemy.start();
enemy1.start();
ammo1.start();
ammoo1.start();
myammoo1.start();
        this.setVisible(true);//窗口可见
        this.requestFocus();//具体办法可以手设焦点。如果焦点有问题，就优先想到它
}
public static void main(String[] arguments)
{
        Pete Penguin = new Pete();
        PetePanel a = new PetePanel();
    }
}class PetePanel extends JPanel{
    Image petePics[] = new Image[4];
Image petePics1[] = new Image[4];
Image petePics2[] = new Image[4];
Image petePics3[] = new Image[4];
Image petePics4[] = new Image[4];
Image petePics5[] = new Image[4];
    Image back;
    int current = 0;
    int x = 100;
    int y = 100;
int current1 = 0;
    int x1 = 300;
    int y1 = 300;
int current2 = 0;
    int x2 = 400;
    int y2 = 50;
int current3 = 0;
    int x3 = -20;
    int y3 = -20;
int current4 = 0;
    int x4 = -20;
    int y4 = -20;
int current5 = 0;
    int x5 = -20;
    int y5 = -20;
int live=1;
PetePanel() 
{
        super();
        String peteSrc[] = { "right.jpg", "left.jpg", "up.jpg", "down.jpg" };
String peteSrc1[] = { "right.jpg", "left.jpg", "up.jpg", "down.jpg" };
String peteSrc2[] = { "right.jpg", "left.jpg", "up.jpg", "down.jpg" };
String peteSrc3[] = { "ar.jpg", "al.jpg", "au.jpg", "ad.jpg" };
String peteSrc4[] = { "ar.jpg", "al.jpg", "au.jpg", "ad.jpg" };
String peteSrc5[] = { "ar.jpg", "al.jpg", "au.jpg", "ad.jpg" };
        Toolkit kit = Toolkit.getDefaultToolkit();
        for (int i = 0; i < petePics.length; i++) 
{
            petePics[i] = kit.getImage(peteSrc[i]);
            petePics1[i] = kit.getImage(peteSrc1[i]);
petePics2[i] = kit.getImage(peteSrc2[i]);
petePics3[i] = kit.getImage(peteSrc3[i]);
petePics4[i] = kit.getImage(peteSrc4[i]);
petePics5[i] = kit.getImage(peteSrc5[i]);
        }
        back = kit.getImage("30.jpg");
    }    public void paint(Graphics comp) //创建绘图函数
{
        Graphics2D comp2D = (Graphics2D) comp;
        if (petePics[current] != null)
 comp2D.drawImage(back,0,0,this);
            comp2D.drawImage(petePics[current], x, y, this);
comp2D.drawImage(petePics1[current1], x1, y1, this);
comp2D.drawImage(petePics2[current2], x2, y2, this);
comp2D.drawImage(petePics3[current3], x3, y3, this);
comp2D.drawImage(petePics4[current4], x4, y4, this);
comp2D.drawImage(petePics5[current5], x5, y5, this);
    }
}
class myammoo extends Thread
{
PetePanel pete ;
public myammoo(PetePanel pete)
{
this.pete=pete;
}
public void run()
{
for(;true;){
while(pete.live==1)
{
if(pete.current==0)
{
System.out.println("Thread is live");
pete.current5=0;
pete.x5=pete.x+10;
pete.y5=pete.y+10;
for(int i=0;i<500;i++)
{
  pete.x5=pete.x5+1;
   pete.y4=pete.y4+1;
  try
  {
                          sleep(1); //线程休眠
                      }
                      catch(InterruptedException e){}
  pete.repaint();
}
}
else if(pete.current==1)
{
pete.current5=1;
pete.x5=pete.x+10;
pete.y5=pete.y+10;
for(int i=0;i<500;i++)
{
  pete.x5=pete.x5-1;
   pete.y4=pete.y4+1;
  try
  {
                          sleep(1); //线程休眠
                      }
                      catch(InterruptedException e){}
  pete.repaint();
}
}
else if(pete.current==2)
{
pete.current5=2;
pete.x5=pete.x+10;
pete.y5=pete.y+10;
for(int i=0;i<500;i++)
{
  pete.y5=pete.y5-1;
   pete.y4=pete.y4+1;
  try
  {
                          sleep(1); //线程休眠
                      }
                      catch(InterruptedException e){}
  pete.repaint();
}
}
else if(pete.current==3)
{
pete.current5=3;
pete.x5=pete.x+10;
pete.y5=pete.y+10;
for(int i=0;i<500;i++)
{
  pete.y5=pete.y5+1;
   pete.y4=pete.y4+1;
  try
  {
                          sleep(1); //线程休眠
                      }
                      catch(InterruptedException e){}
  pete.repaint();
}
}
 pete.x5=0-20;
 pete.y5=0-20;
 try
  {
                          sleep(1000); //线程休眠 
                      }
                      catch(InterruptedException e){}
}
}}
}