目前,我有以下情況:的NullPointerException在JavaFX應用程序線程ENTER鍵按下
我想讓我的應用程序聽取用戶的輸入。首先,我用一個看不見的TextField做了這個,但是這個搞砸了我的設計,我認爲它不夠複雜。所以,我現在想做一個onKeyPressed事件處理在我的上FlowPane,像這樣:
public String input = "";
@FXML public void listenToInput(KeyEvent key) {
if (key.getCode() != KeyCode.ENTER) {
if (key.getCode().isDigitKey() || key.getCode().isLetterKey()) {
String newChar = key.getText();
input = input.concat(newChar);
}
}
else {
this.addScanToList(input);
input = "";
}
}
這工作只是簡單的文本和數字。但只要我按ENTER,我得到以下錯誤:
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.sun.javafx.scene.control.behavior.TableViewBehaviorBase.activate(TableViewBehaviorBase.java:915)
at com.sun.javafx.scene.control.behavior.TableViewBehaviorBase.callAction(TableViewBehaviorBase.java:179)
at com.sun.javafx.scene.control.behavior.BehaviorBase.callActionForEvent(BehaviorBase.java:218)
at com.sun.javafx.scene.control.behavior.TableViewBehaviorBase.callActionForEvent(TableViewBehaviorBase.java:208)
at com.sun.javafx.scene.control.behavior.BehaviorBase.lambda$new$75(BehaviorBase.java:135)
at com.sun.javafx.scene.control.behavior.BehaviorBase$$Lambda$146/1103773754.handle(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$KeyHandler.process(Scene.java:3926)
at javafx.scene.Scene$KeyHandler.access$1800(Scene.java:3872)
at javafx.scene.Scene.impl_processKeyEvent(Scene.java:2001)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:2463)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:197)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:147)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleKeyEvent$346(GlassViewEventHandler.java:228)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$208/996795822.get(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:406)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:227)
at com.sun.glass.ui.View.handleKeyEvent(View.java:540)
at com.sun.glass.ui.View.notifyKey(View.java:950)
在那裏我已經想到了:
- 上FlowPane沒有焦點,但後來我把它集中,但沒有結果。
- 回車鍵沒有被識別,這可能是真的,因爲我的listenToInput的'其他'永遠不會被輸入。
編輯1:
- 的FlowPane沒有一個 'setOnAction',所以它不知道如何處理ENTER按。
有誰知道是什麼觸發了這個錯誤?
編輯2:
我改變onKeyPressed到onKeyReleased,然後我的代碼運行正常,但我仍然得到錯誤。也許這有助於瞭解這一點。
編輯3:
我試圖掃描添加到列表中與ALT,而不是ENTER,而這完美的作品,所以有事情做與ENTER
感謝您的回答!我已經在FXML文件中設置了這個動作,那麼它與你所建議的基本不一樣? – bashoogzaad 2014-12-09 20:37:59