我試圖做一個切換按鈕(F)隱藏或顯示我的聊天區(JTextArea中),這是JScrollPane上(SP)和它不工作...爪哇 - NullPointerException異常
這裏是什麼我做...
我有它設置爲公共...
public JScrollPane sp;
,我把它的init()
像這裏面: JScrollPane sp = new JScrollPane(c);
c
是JTextArea中....
if (e.getKeyCode() == KeyEvent.VK_F)
{
if (sp.isVisible())
{
sp.setVisible(false);
}
else
{
sp.setVisible(true);
}
}
這是我的錯誤:
Exception in thread "AWT-EventQueue-2" java.lang.NullPointerException
at tileGen.keyPressed(tileGen.java:522)
at java.awt.Component.processKeyEvent(Unknown Source)
at javax.swing.JComponent.processKeyEvent(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.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(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.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)
這是行522:if (sp.isVisible()) {
我在做什麼錯?
因此,他可以問一個關於StackOverflow的問題:-) – Douglas 2010-08-18 23:29:16
哦,我想我應該從JScrollPane中取出JScrollPane sp = new JScrollPane(c);! – nn2 2010-08-19 00:01:21
謝謝,這工作! – nn2 2010-08-19 00:02:21