Java NullPointerException在我的代码中，我无法消除它

我收到以下错误，无法识别发生了什么。 我是java新手，尝试使用java框架制作人字拖游戏。请帮忙

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(ImageIcon.java:217)
    at FlipFlopFrame.setCards(FlipFlopFrame.java:24)
    at FlipFlopFrame.<init>(FlipFlopFrame.java:18)
    at FlipFlopFrame$1.run(FlipFlopFrame.java:285)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

这些声明

getClass().getResource("../images/card"+numbers[0]+".png" ...

…可能正在返回

null

不确定为什么在此处使用相对路径（即

。/images/card

）

如果你的类路径上有一个名为“images”的文件夹下的图像，那么你可能只需要

getClass().getResource("/images/card"+numbers[0]+".png" ...

---

请参见此图，以确保第217行中引用的图像实际上作为资源库存在。非常感谢，先生

getClass().getResource("/images/card"+numbers[0]+".png" ...