菜鸟求助 Unknown Source 怎么解决？

Question

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at main.Login$1.actionPerformed(Login.java:110)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

Login.java文件第110行有对象是Null的，仔细查查这里的代码。

Answer 2

这些Unknown source原因应该是，Login.java:110行的NullPointerException导致引用到swing包的api发生异常。。而swing的jar包没有关联到swing的源码

Answer 3

可以在myeclipse中将swing jar包关联到其源码上就行。。用处是：为了调试swing的内部api执行时用到

Answer 4

main.Login类中某个匿名内部类的actionPerformed方法中出现了null对象不过这应该是个mouseRelease事件吧/**
   * Accept a mouse release event and set the button's 
   * "pressed" property to <code>true</code>, if the model
   * is armed. If the model is not armed, ignore the event.
   *
   * @param e The mouse release event to accept
   */
  public void mouseReleased(MouseEvent e)
  {
    if (e.getSource() instanceof AbstractButton)
      {
        AbstractButton button = (AbstractButton) e.getSource();
        ButtonModel model = button.getModel();
        if ((e.getModifiersEx() & InputEvent.BUTTON1_DOWN_MASK) != 0)
          {
            // It is important that these transitions happen in this order.
            model.setPressed(false);
            model.setArmed(false);
          }
      }
  }

Answer 5

这些Unknown source原因应该是，Login.java:110行的NullPointerException导致引用到swing包的api发生异常。。而swing的jar包没有关联到swing的源码