java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null
at java.desktop/javax.swing.ImageIcon.(ImageIcon.java:234)
at com.artisan.view.LoginFrm.(LoginFrm.java:68)
at com.artisan.view.LoginFrm$1.run(LoginFrm.java:46)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:771)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:741)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null
location为空导致空指针异常了。
这不提示NullPointerException，because "location" is null，LoginFrm.java:68行，你传了一个未初始化的变量