使用ArrayList繪製圖像（JPanel，JFrame）

Question

我在使用ArrayList在JPanel/Jframe內繪製多個圖像時遇到了一些麻煩。我的項目是創建一個Yar的復仇類遊戲。到目前爲止，沒有在附近這一點，但這裏是我有：

import java.awt.Color; 
import java.awt.Component; 
import java.awt.Graphics; 
import java.awt.Image; 
import java.awt.Toolkit; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.KeyEvent; 
import java.awt.event.KeyListener; 
import java.awt.image.ImageObserver; 
import java.util.ArrayList; 
import javax.swing.JPanel; 

public class GamePanel extends JPanel implements ActionListener, KeyListener, ImageObserver { 
     public Image ship; 
     public Image enemy; 
     public Image shot; 
     private int xLoc; 
     private int yLoc = 180; 
     private int xLoc2 = 700; 
     private int yLoc2 = 180; 
     private int xVel; 
     private int yVel; 
     private int xVel_en; 
     private int xVel_sh; 
     private ImageObserver observer; 
     private ArrayList<Base> shield = new ArrayList<Base>(); 
     private Image shieldPiece; 

     public GamePanel() { 
      ship = Toolkit.getDefaultToolkit().createImage("ship3.png"); 
      enemy = Toolkit.getDefaultToolkit().createImage("alien-ship-1.png"); 
      shot = Toolkit.getDefaultToolkit().createImage("shot4.png"); 
      shieldPiece = Toolkit.getDefaultToolkit().createImage("block1.png"); 

      for(int x = 300; x < 420; x = x + 30) 
       for(int y = 100; y < 220; y = y + 30) { 
        Base temp = new Base(x,y); 
        shield.add(temp); 
       } 
     } 

     public void paint(Graphics g){ 
      super.paint(g); 
      g.drawImage(ship, xLoc, yLoc, null); 
      //g.drawImage(enemy, xLoc2, yLoc2, null); 

      for(Base b: shield) 
       g.drawImage(shieldPiece, b.getShieldX(), b.getShieldY(), null); 
     } 

     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      // TODO Auto-generated method stub 

      move(); 
      setBackground(Color.BLACK); 
      repaint(); 

     } 

     private void move() { 

      int endOfWindow = getWidth(); 
      int endOfWindow1 = getHeight(); 
      if(xLoc>=(endOfWindow - ship.getWidth(null))|| xLoc<0) 
       xVel = -xVel; 
      xLoc +=xVel;  
      if(xLoc>=(endOfWindow - ship.getWidth(null))) 
       xVel = -xVel; 
      xLoc +=xVel; 
      if(yLoc>=(endOfWindow1 - ship.getHeight(null)) || yLoc<0) 
       yVel = -yVel; 
      yLoc +=yVel; 
      if(yLoc>=(endOfWindow1 - ship.getHeight(null))) 
       yVel = -yVel; 
      yLoc +=yVel; 

     } 

     @Override 
     public void keyPressed(KeyEvent arg0) { 
      // TODO Auto-generated method stub 

      if(arg0.getKeyCode() == KeyEvent.VK_D) 
       xVel = 3; 
      if(arg0.getKeyCode() == KeyEvent.VK_A) 
       xVel = -3; 
      if(arg0.getKeyCode() == KeyEvent.VK_W) 
       yVel = -3; 
      if(arg0.getKeyCode() == KeyEvent.VK_S) 
       yVel = 3; 

      if(arg0.getKeyCode() == KeyEvent.VK_RIGHT) 
       xVel = 3; 
      if(arg0.getKeyCode() == KeyEvent.VK_LEFT) 
       xVel = -3; 
      if(arg0.getKeyCode() == KeyEvent.VK_UP) 
       yVel = -3; 
      if(arg0.getKeyCode() == KeyEvent.VK_DOWN) 
       yVel = 3; 

      //if(arg0.getKeyCode() == KeyEvent.VK_SPACE) 



     } 

     @Override 
     public void keyReleased(KeyEvent arg0) { 
      // TODO Auto-generated method stub 

      if(arg0.getKeyCode() == KeyEvent.VK_D || arg0.getKeyCode() == KeyEvent.VK_A) 
       xVel = 0; 
      if(arg0.getKeyCode() == KeyEvent.VK_W || arg0.getKeyCode() == KeyEvent.VK_S) 
       yVel = 0; 

      if(arg0.getKeyCode() == KeyEvent.VK_RIGHT || arg0.getKeyCode() == KeyEvent.VK_LEFT) 
       xVel = 0; 
      if(arg0.getKeyCode() == KeyEvent.VK_UP || arg0.getKeyCode() == KeyEvent.VK_DOWN) 
       yVel = 0; 

     } 

     @Override 
     public void keyTyped(KeyEvent arg0) { 
      // TODO Auto-generated method stub 

     } 
} 

，這裏是我的基類：

import java.awt.Color; 
import java.awt.event.KeyListener; 
import javax.swing.JFrame; 
import javax.swing.Timer; 

public class GameWindow extends JFrame { 

    public GameWindow() { 
     setSize(800, 500); 
     GamePanel pan = new GamePanel(); 
     Timer t = new Timer(40, pan); 
     add(pan); 
     this.addKeyListener(pan); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     t.start(); 

    } 

    /** 
    * @param args 
    */ 
    public static void main(String[] args) { 
     // TODO Auto-generated method stub 

    } 

} 

annnnd是這樣的：參考

import java.awt.Image; 
import java.awt.Toolkit; 


public class Base { 
    private Image shieldPiece; 
    private int x; 
    private int y; 

    public Base(int xCoord, int yCoord) { 
     xCoord = x; 
     yCoord = y; 
      } 

    public int getShieldX() { 
     return x; 
    } 

    public int getShieldY() { 
     return y; 
    } 

} 

GameWindow類什麼彈出：

http://i.imgur.com/4bmf3Ab.png

它應該在船的右側（從x = 300，y = 100開始）繪製多個屏蔽件（紅色矩形）。窗口是800x500。我不確定爲什麼它不通過數組列表循環繪製每一部分。任何人都可以幫我嗎？

Answer 1

，我發現到現在的原因是這樣的：

public Base(int xCoord, int yCoord) { 
    xCoord = x; 
    yCoord = y; 
} 

要分配xCoord的x和yCoord其價值是由0的default.It的y值應改爲：

public Base(int xCoord, int yCoord) { 
x = xCoord ; 
y = yCoord ; 
}