我试图在jpanel上显示两个物体坦克，坦克用imageicon获得图像。喷气式飞机出现了，但我的坦克没有。我找不到我错在哪里。我的一个朋友给我发的代码，他可以显示坦克，但我不能用我的电脑显示它。
我的坦克类得到图像

public class Player extends Tank {
private Image img;

public Player(int x, int y){
    super(x, y);
    ImageIcon ii = new ImageIcon("src/TankD.gif");
    img = ii.getImage();
}

public Image getImg() {
    return img;
}
public String toString() {
    return "This is player tank";
}

}
我的课画图像

public class DrawTanks extends JPanel{  // DRAW IMAGE

private ArrayList<Tank> list = new ArrayList<>();
private Tank a;
public DrawTanks() {
    Tank t1 = new Player(100, 200);
    Tank t2 = new Bot(200, 100);
    a = t1;
    list.add(t1);
    list.add(t2);
    setPreferredSize(new Dimension(100,200));
    setLocation(new Point(200, 200));

}

@Override
public void paintComponent(Graphics g){
    for (Tank i: list)
        g.drawImage(i.getImg(), i.getX(), i.getY(), null);
}

我的主课

public class Window extends JFrame{
public static void main(String[]args){
    Window win = new Window();
}
public Window(){
    JPanel pan = new JPanel();
    DrawTanks tanks = new DrawTanks();
    this.add(tanks);
    this.setTitle("Tank");
    this.setSize(900,900);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    this.setLocationRelativeTo(null);
    this.setVisible(true);
}

}