图标处理抛出NullPointerException

我添加了一个形象我的jList元素，但是当我运行框架这将引发异常：图标处理抛出NullPointerException

java.lang.NullPointerException 
at javax.swing.ImageIcon.<init>(ImageIcon.java:217) 
at org.openstreetmap.josm.plugins.laneconnector.LaneRelationsDialog.createImageMap(LaneRelationsDialog.java:527) 
at org.openstreetmap.josm.plugins.laneconnector.LaneRelationsDialog.<init>(LaneRelationsDialog.java:363) 
at org.openstreetmap.josm.plugins.laneconnector.LaneRelationsAction.actionPerformed(LaneRelationsAction.java:38) 
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1663) 
at javax.swing.JComponent.processKeyBinding(JComponent.java:2879) 
at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:307) 
at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:263) 
at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2971) 
at javax.swing.JComponent.processKeyBindings(JComponent.java:2963) 
at javax.swing.JComponent.processKeyEvent(JComponent.java:2842) 
at java.awt.Component.processEvent(Component.java:6304) 
at java.awt.Container.processEvent(Container.java:2234) 
at java.awt.Component.dispatchEventImpl(Component.java:4883) 
at java.awt.Container.dispatchEventImpl(Container.java:2292) 
at java.awt.Component.dispatchEvent(Component.java:4705) 
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954) 
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:806) 
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1074) 
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:945) 
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:771) 
at java.awt.Component.dispatchEventImpl(Component.java:4754) 
at java.awt.Container.dispatchEventImpl(Container.java:2292) 
at java.awt.Window.dispatchEventImpl(Window.java:2739) 
at java.awt.Component.dispatchEvent(Component.java:4705) 
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746) 
at java.awt.EventQueue.access$400(EventQueue.java:97) 
at java.awt.EventQueue$3.run(EventQueue.java:697) 
at java.awt.EventQueue$3.run(EventQueue.java:691) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75) 
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86) 
at java.awt.EventQueue$4.run(EventQueue.java:719) 
at java.awt.EventQueue$4.run(EventQueue.java:717) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75) 
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716) 
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)

行217：

 public ImageIcon(URL location){ 
    this(location, location.toExternalForm());}

行527：

map.put(s, new ImageIcon(getClass().getResource("/images/right.png")));

我检查的System.out.println（的getClass（）的getResource（ “/图片/ right.png”）。）;并返回null。此外，我复制此图片在bin文件夹，但错误是相同的。为什么？请帮帮我！

来源

2015-02-10 Adrian Trifan

为使getClass（）。getResource（）正常工作，图标需要与.class文件位于同一目录树中。你如何编写你的应用程序？ – yole 2015-02-10 08:08:03

你看过文档或样例用法吗？ – keyser 2015-02-10 08:08:37

不要在任何地方手动放置任何.png文件。使用Ant，Maven，Gradle或者您最喜欢的IDE来为您编译项目。另外我猜想你的第二个代码片段中的路径在开始时不应该包含“resources”。 – yole 2015-02-10 08:25:11

getResource()查找具有给定名称的资源。用于搜索与给定类关联的资源的规则由类的定义类加载器来实现。

确保您的文件存在于类路径或项目中。

来源

2015-02-10 08:11:33

图标处理抛出NullPointerException

回答

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