java中为什么组件不显示出来

代码如下

 public class Snake extends JFrame{

    private Icon icon1;
    private Icon icon2;
    private JLabel[] num;
    private URL url1;
    private URL url2;
    /**
     * 
     */
    private static final long serialVersionUID = -7453810388329378685L;
    public static void main(String[] args){
        new Snake();
        }
    public Snake(){
        num=new JLabel[10000];
        url1=Snake.class.getResource("hollowsquare.png");
        url2=Snake.class.getResource("solidsquare.png");
        icon1=new ImageIcon(url1);
        icon2=new ImageIcon(url2);
        Container c=getContentPane();
        c.setLayout(new GridLayout(1,1,0,0));
        JPanel jp=new JPanel();
        jp.setLayout(new GridLayout(100,100,0,0));
        c.add(jp);
        for(int i=0;i<10000;i++){
            System.out.println("running"+i);
            num[i]=new JLabel();
            num[i].setSize(5, 5);
            num[i].setIcon(icon2);
            num[i].setVisible(true);
            jp.add(num[i]);
        }
        setResizable(false);   //不允许更改大小
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 500, 500);
        setVisible(true);
    }
}

不显示不报错吗？我觉得你应该是图片没有找到，报了一个空指针异常的错吧？