Java 问题求助
本帖最后由 oooooook 于 2021-10-18 11:04 编辑这paint方法里边obj.draw(g);[里边有i]循环运行没有图
这个paint方法把obj.draw(g);里边的i变成具体数字obj.draw(g);就有图了
我这是哪里打错了
这个是报错的内容：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at man.Man$DrawMan.paint(Man.java:23)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:586)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5226)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1572)
at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1495)
at javax.swing.RepaintManager.paint(RepaintManager.java:1265)
at javax.swing.JComponent.paint(JComponent.java:1042)
at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:39)
at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:79)
at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:116)
at java.awt.Container.paint(Container.java:1973)
at java.awt.Window.paint(Window.java:3912)
at javax.swing.RepaintManager$4.run(RepaintManager.java:835)
at javax.swing.RepaintManager$4.run(RepaintManager.java:807)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:807)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:782)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:731)
at javax.swing.RepaintManager.access$1300(RepaintManager.java:64)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1720)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:749)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:702)
at java.awt.EventQueue$3.run(EventQueue.java:696)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:719)
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)
Process finished with exit code 0
这个是不是因为我的for里边的循环数与数组赋值的数不同
java.lang.NullPointerException，空指针异常
obj、obj的值为null，没有赋初值
你把循环里的内容改为i<3试试 巴巴鲁 发表于 2021-10-19 10:00
java.lang.NullPointerException，空指针异常
obj、obj的值为null，没有赋初值
你把循环里的内容改 ...
太对了，哥
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