JavaFX如何取消组合框选择更改?
以下是演示代码:JavaFX如何取消组合框选择更改?,java,javafx,combobox,Java,Javafx,Combobox,以下是演示代码: 公共类ComboBoxTest扩展应用程序{ 公共静态void main(字符串[]args){ Application.launch(ComboBoxTest.class); } @凌驾 public void start(Stage primaryStage)引发异常{ ComboBox ComboBox=新建ComboBox(); comboBox.getItems().addAll(“选项1”、“选项2”、“选项3”); comboBox.getSelectionMod
公共类ComboBoxTest扩展应用程序{
公共静态void main(字符串[]args){
Application.launch(ComboBoxTest.class);
}
@凌驾
public void start(Stage primaryStage)引发异常{
ComboBox ComboBox=新建ComboBox();
comboBox.getItems().addAll(“选项1”、“选项2”、“选项3”);
comboBox.getSelectionModel().select(0);
comboBox.getSelectionModel().SelectEditeProperty().addListener(
(\u ob,\u old,\u new)->{
如果(!isValidChange(_旧,_新)){
//错误:尝试取消更改并获取StackOverflower错误
comboBox.getSelectionModel().select(_old);
}
});
初级阶段。设置场景(新场景)(
新的边框窗格(组合框),300200);
primaryStage.show();
}
私有静态布尔值isValidChange(字符串旧,字符串新){
//返回false;
返回!_old.equals(“选项1”);
}
}
当更改组合框的选择时,它通常会抛出堆栈溢出错误,我知道原因(一次又一次地触发ChangeListener
对象),但我不知道的是如何正确地“取消”此选择更改操作
更新:
抱歉@fabian我在这里写了一个糟糕的例子,让我稍微修改一下:
private static boolean isValidChange(String _old, String _new) {
return !_old.equals("option1");
}
它现在可以工作了,组合框
值不能更改。然而,我在这里得到一个奇怪的索引outofboundsexception
,而堆栈跟踪中没有我的代码行:
Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.subList(ReadOnlyUnbackedObservableList.java:136)
at javafx.collections.ListChangeListener$Change.getAddedSubList(ListChangeListener.java:242)
at com.sun.javafx.scene.control.behavior.ListViewBehavior.lambda$new$177(ListViewBehavior.java:269)
at javafx.collections.WeakListChangeListener.onChanged(WeakListChangeListener.java:88)
at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:329)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:73)
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.callObservers(ReadOnlyUnbackedObservableList.java:75)
at javafx.scene.control.MultipleSelectionModelBase.clearAndSelect(MultipleSelectionModelBase.java:378)
at javafx.scene.control.ListView$ListViewBitSetSelectionModel.clearAndSelect(ListView.java:1403)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.simpleSelect(CellBehaviorBase.java:256)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.doSelect(CellBehaviorBase.java:220)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:150)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$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.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$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:380)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)
这是JavaFX的错误吗?这里有两个问题
从值A
更改为值b
无效,但从b
更改为A
无效。因此,当值更改时,侦听器会撤消更改,这会导致侦听器尝试撤消的另一个更改事件,侦听器再次尝试撤消该事件
您可以修改选择模型。但是,选择模型依赖于选择保持不变
要解决这些问题,请引入一个ChangeListener
,它“知道何时否决更改”,并在使用平台处理更改事件后运行更改。稍后运行:
public abstract class VetoListener<T> implements ChangeListener<T> {
private final SelectionModel<T> selectionModel;
private boolean changing = false;
public VetoListener(SelectionModel<T> selectionModel) {
if (selectionModel == null) {
throw new IllegalArgumentException();
}
this.selectionModel = selectionModel;
}
@Override
public void changed(ObservableValue<? extends T> observable, T oldValue, T newValue) {
if (!changing && isInvalidChange(oldValue, newValue)) {
changing = true;
Platform.runLater(() -> {
selectionModel.select(oldValue);
changing = false;
});
}
}
protected abstract boolean isInvalidChange(T oldValue, T newValue);
}
这里有两个问题
从值A
更改为值b
无效,但从b
更改为A
无效。因此,当值更改时,侦听器会撤消更改,这会导致侦听器尝试撤消的另一个更改事件,侦听器再次尝试撤消该事件
您可以修改选择模型。但是,选择模型依赖于选择保持不变
要解决这些问题,请引入一个ChangeListener
,它“知道何时否决更改”,并在使用平台处理更改事件后运行更改。稍后运行:
public abstract class VetoListener<T> implements ChangeListener<T> {
private final SelectionModel<T> selectionModel;
private boolean changing = false;
public VetoListener(SelectionModel<T> selectionModel) {
if (selectionModel == null) {
throw new IllegalArgumentException();
}
this.selectionModel = selectionModel;
}
@Override
public void changed(ObservableValue<? extends T> observable, T oldValue, T newValue) {
if (!changing && isInvalidChange(oldValue, newValue)) {
changing = true;
Platform.runLater(() -> {
selectionModel.select(oldValue);
changing = false;
});
}
}
protected abstract boolean isInvalidChange(T oldValue, T newValue);
}
谢谢你解决了我的StackOverflowerr
问题,但现在有一个新问题,我更新了我的帖子。谢谢!你解决了我的StackOverflowerError
问题,但现在有一个新问题,我更新了我的帖子。更新后:你唯一要做的就是包装comboBox.getSelectionModel().select(_old)将>编码到Platform.runLater(…)
类似Platform.runLater(()->comboBox.getSelectionModel().select(_old))的块中
@DVarga它现在可以工作了,谢谢更新:你唯一要做的就是包装comboBox.getSelectionModel().select(_old)将>编码到Platform.runLater(…)
类似Platform.runLater(()->comboBox.getSelectionModel().select(_old))的块中代码>@DVarga现在可以用了,谢谢