图标处理抛出 NullPointerException

Question

我已经为我的 Jlist 元素添加了一个图像，但是当我运行该帧时将抛出此异常：

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.access0(EventQueue.java:97)
at java.awt.EventQueue.run(EventQueue.java:697)
at java.awt.EventQueue.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue.run(EventQueue.java:719)
at java.awt.EventQueue.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain.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)

第 217 行：

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

第 527 行：

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

我检查了 System.out.println(getClass().getResource("/images/right.png")); returns 为空。另外，我将这张图片复制到bin文件夹中，但错误是一样的。为什么？请帮我！

Answer 1

getResource() 查找具有给定名称的资源。搜索与给定 class 关联的资源的规则由 class 的定义 class 加载器实现。

确保您的文件存在于 class 路径或项目中。

图标处理抛出 NullPointerException

Icon Handling throw a NullPointerException

java

swing

exception