一个构造器参数传递问题

Question

public Tank(int[] Enemy,String[] EnemyDir)
   {
this.Enemy=Enemy;
this.EnemyDir=EnemyDir;
       
   }
paintComponent(Graphics g).....
我传递了一个组数给这个构造器，而且如果我在构造器内部可以正确的打印数组，为什么在paintComponent方法中打印数组的
时候全是0和NULL？

Answer 1

import   java.awt.*;   
  import   java.awt.geom.*;   
  import   java.awt.geom.Point2D.Double;   
  import   java.util.*;   
  import   java.awt.event.*;   
  import   javax.swing.*;  
  import   javax.swing.event.*; public class TankBattle
{
    public static void main(String[] args)
    {
EventQueue.invokeLater(new Runnable()
         {
public void run()
{
    GameFrame frame=new GameFrame();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
    });
    }
}
class GameFrame extends JFrame
{
    public GameFrame()
    {
setTitle("TankBattle");
setSize(DW,DH);
//坦克组
       for(int i=0;i<8;i++)
       {
   Enemy[i]=i*100;
   EnemyDir[i]="D";
       }
Tank ETank=new Tank(Enemy,EnemyDir);
Tank tank=new Tank(DW/2,DH-100,Enemy.length,"U");
tank.setFocusable(true);
add(tank);
setResizable(false);
    }
    private  static int DW=800;
    private  static int DH=600;
    private int[] Enemy=new int[8];
    private String[] EnemyDir=new String[8];
}
class Tank extends JComponent
{
    private static Toolkit tk = Toolkit.getDefaultToolkit();
    private static Image[] tankImages = null;
    private static Image[] missileImages = null;
    private static Map<String, Image> imgs = new HashMap<String, Image>();
    private static Map<String, Image> imgs1 = new HashMap<String, Image>();
    static {
        tankImages = new Image[]
                {
tk.getImage(Tank.class.getClassLoader().getResource("images/tankL.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankLU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankRU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankR.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankRD.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankD.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/tankLD.gif"))
};

                imgs.put("L", tankImages[0]);
     imgs.put("LU", tankImages[1]);
     imgs.put("U", tankImages[2]);
            imgs.put("RU", tankImages[3]);
     imgs.put("R", tankImages[4]);
     imgs.put("RD", tankImages[5]);
     imgs.put("D", tankImages[6]);
     imgs.put("LD", tankImages[7]);
     }
static {
missileImages = new Image[] {
tk.getImage(Tank.class.getClassLoader().getResource("images/missileL.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileLU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileRU.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileR.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileRD.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileD.gif")),
tk.getImage(Tank.class.getClassLoader().getResource("images/missileLD.gif"))
};

imgs1.put("L", missileImages[0]);
imgs1.put("LU", missileImages[1]);
imgs1.put("U", missileImages[2]);
imgs1.put("RU", missileImages[3]);
imgs1.put("R", missileImages[4]);
imgs1.put("RD", missileImages[5]);
imgs1.put("D", missileImages[6]);
imgs1.put("LD", missileImages[7]);

}
   public Tank(int x,int y,int length,String dir)
   {
this.x=x;
this.y=y;
this.length=length;
addKeyListener(new keyHandler());
this.dir=dir;         

   }
   public Tank(int x,int y,String dirCannon)
   {
this.dirCannon=dirCannon;
   }
   public Tank(int[] Enemy,String[] EnemyDir)
   {
this.Enemy=Enemy;
this.EnemyDir=EnemyDir;
       
   }
  
   
   public void paintComponent(Graphics g)
   {
       Graphics2D g2=(Graphics2D)g;
       g2.drawImage(imgs.get(dir),x,y,null);
 for(i=0;i<8;i++)
         {
    g2.drawImage(imgs.get(EnemyDir[i]),Enemy[i],0,null);
 }
if(fire)
        {
    g2.drawImage(imgs1.get(dirCannon),CannonX,CannonY,null);
}
Runnable r=new paintRunnable();
        Thread t=new Thread(r);
        t.start();
   }
   private class keyHandler implements KeyListener
   {
public void keyPressed(KeyEvent event)
{
    int keyCode=event.getKeyCode();
         if(keyCode==KeyEvent.VK_W)
    {
dir="U";
        y-=5;
    Tank tank=new Tank(x,y,length,dir);
    }
    if(keyCode==KeyEvent.VK_S)
    {
dir="D";
        y+=5;
    Tank tank=new Tank(x,y,length,dir);
    }
    if(keyCode==KeyEvent.VK_A)
    {
dir="L";
        x-=5;
    Tank tank=new Tank(x,y,length,dir);
    }
    if(keyCode==KeyEvent.VK_D)
    {
dir="R";
        x+=5;
    Tank tank=new Tank(x,y,length,dir);
    }
    if(keyCode==KeyEvent.VK_H)
    {
fire=true;
if(Ready)
{
    CannonX=x;
    CannonY=y;
}
if(CannonX>0&&CannonY>0)
 dirCannon=dir;
Ready=false;

    }
}

  
public void keyReleased(KeyEvent event)
{
}
public void keyTyped(KeyEvent event)
{
}
    }   private class paintRunnable implements Runnable
   {
       public void run()
       {
    try
    {
    if(!Ready)
    {
    if(dirCannon=="U")
    {

           CannonY-=10;
     Tank cannon=new Tank(CannonX,CannonY,"U");
    }
    if(dirCannon=="D")
    {

           CannonY+=10;
     Tank cannon=new Tank(CannonX,CannonY,"D");
    }
    if(dirCannon=="R")
    {

           CannonX+=10;
     Tank cannon=new Tank(CannonX,CannonY,"R");
    }
    if (dirCannon=="L")
    {
           CannonX-=10;
     Tank cannon=new Tank(CannonX,CannonY,"L");
    }
    
    }
if(CannonY<0||CannonX<0||CannonY>600||CannonX>800)
{
    Ready=true;
}
               repaint();
       Thread.sleep(5);
    }
    catch(InterruptedException e)
    {
    }
       }
    }
    private boolean Ready=true;
    private boolean fire;  
    private static int x;
    private static int y;
    private static int i;
    private static int CannonX;
    private static int CannonY;
    private String dir;
    private String dirCannon;
    private static int length;
    private int[] Enemy=new int[8];
    private String[] EnemyDir=new String[8];
    private int[] Enemy1=new int[8];
    private String[] EnemyDir1=new String[8];
}自已写的，GIF是从马士兵的程序中弄出来的，新手写得很生涩，而且只写了一部份，主要是我想把这个数组传过去画出敌方的坦克组，但是数组一到PAINTCOMPONENT方法中就全变成0和NULL了

Answer 2

哈哈，我在做那个BBS，等你的结果啦

Answer 3

传值的方法有问题！！！
已经建立了对象private String[] EnemyDir=new String[8]; 
应该用for循环给EnemyDir赋值：
for (int i = 0; i < EnemyDir.length; i++) {
    EnemyDir[i] = EnemyDir[i];}

Answer 4

如果你确认那个Tank就是你的那个Tank,那么我只能说，其实他不是。
你画图的那个tank估计已经被变动了！

Answer 5

将 paintComponent 方法中的
g2.drawImage(imgs.get(EnemyDir[i]),Enemy[i],0,null); 
改为这样试试：
g2.drawImage(imgs.get(this.EnemyDir[i]), this.Enemy[i],0,null);