JavaFx：組合框表單元格雙擊

Question

問題如下：

我有一個帶有ComboBoxes的TableView ，對於每個TableCell，我都可以從組合框中選擇一個值。 問題是，如果我有很多行和列，我必須單擊很多以在每個comboBox中選擇適當的值。 要在組合框中選擇一個值，我必須單擊四次以選擇該值。 一次選擇單元格，一次設置組合框的圖形，再次打開組合框的彈出窗口，我可以在其中選擇值，最后選擇值。

我想使用doubleClick，因此可以快速打開comboBox，然后選擇值。 如果我有很多選擇的值，這將節省點擊次數和大量時間。

我試圖解決它，但是所有解決方案都無法正常工作，

我在這里添加它們，也許您可​​以看到我出了錯的地方並進行糾正。

我嘗試了兩種類似的方法：

1. 忽略startEdit（）並向該單元格添加一個mouseclick偵聽器，然后雙擊雙擊組合框。 如果我單擊另一個單元格，即使我將setGrapichs(null)都同時放在cancelEdit和commitEdit ，也不會將圖形設置為null，這會帶來問題。 另一個問題是有時不將值提交給模型。

2. 第二種方法是處理它在startEdit中（），所以只需調用.show()那里， .hide()這兩個提交和取消編輯，這取決於行動。 這給了我一個NPE，如果我將TableView包裹在TitledPane ，然后將其折疊/展開后，我嘗試選擇一個值，雙擊它會得到NPE：

    Exception in thread "JavaFX Application Thread" java.lang.NullPointerException at com.sun.javafx.scene.control.skin.ComboBoxPopupControl.positionAndShowPopup(ComboBoxPopupControl.java:197) at com.sun.javafx.scene.control.skin.ComboBoxPopupControl.show(ComboBoxPopupControl.java:170) at com.sun.javafx.scene.control.skin.ComboBoxBaseSkin.handleControlPropertyChanged(ComboBoxBaseSkin.java:127) at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.handleControlPropertyChanged(ComboBoxListViewSkin.java:159) at com.sun.javafx.scene.control.skin.BehaviorSkinBase.lambda$registerChangeListener$61(BehaviorSkinBase.java:197) at com.sun.javafx.scene.control.MultiplePropertyChangeListenerHandler$1.changed(MultiplePropertyChangeListenerHandler.java:55) at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:89) at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182) at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81) at javafx.beans.property.ReadOnlyBooleanPropertyBase.fireValueChangedEvent(ReadOnlyBooleanPropertyBase.java:72) at javafx.beans.property.ReadOnlyBooleanWrapper.fireValueChangedEvent(ReadOnlyBooleanWrapper.java:103) at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:110) at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:144) at javafx.scene.control.ComboBoxBase.setShowing(ComboBoxBase.java:185) at javafx.scene.control.ComboBoxBase.show(ComboBoxBase.java:391) at stackoverflow.combo.ComboTableCell.startEdit(ComboTableCell.java:47) at javafx.scene.control.TableCell.updateEditing(TableCell.java:556) at javafx.scene.control.TableCell.lambda$new$26(TableCell.java:142) at javafx.beans.WeakInvalidationListener.invalidated(WeakInvalidationListener.java:83) at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:349) at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81) at javafx.beans.property.ReadOnlyObjectPropertyBase.fireValueChangedEvent(ReadOnlyObjectPropertyBase.java:74) at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:102) at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112) at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146) at javafx.scene.control.TableView.setEditingCell(TableView.java:1145) at javafx.scene.control.TableView.edit(TableView.java:1459) at com.sun.javafx.scene.control.behavior.TableCellBehavior.edit(TableCellBehavior.java:108) at com.sun.javafx.scene.control.behavior.TableCellBehavior.edit(TableCellBehavior.java:38) at com.sun.javafx.scene.control.behavior.CellBehaviorBase.handleClicks(CellBehaviorBase.java:271) at com.sun.javafx.scene.control.behavior.TableCellBehaviorBase.simpleSelect(TableCellBehaviorBase.java:218) at com.sun.javafx.scene.control.behavior.TableCellBehaviorBase.doSelect(TableCellBehaviorBase.java:148) at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mouseReleased(CellBehaviorBase.java:159) at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96) 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.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$MouseEventNotification.run(GlassViewEventHandler.java:381) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417) at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416) at com.sun.glass.ui.View.handleMouseEvent(View.java:555) at com.sun.glass.ui.View.notifyMouse(View.java:937) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191) at java.lang.Thread.run(Thread.java:745) 

這是您可以檢查的代碼：

TableCell的：

public class ComboTableCell<T,S> extends TableCell<T,S> {

    private ComboBox<S> combo;

    public ComboTableCell(Collection<S> items) {
        combo = new ComboBox<>();
        combo.setItems(FXCollections.observableArrayList(items));
        combo.prefWidthProperty().bind(widthProperty());
        combo.valueProperty().addListener((observable, oldValue, newValue) -> commitEdit(newValue));
//      1. Solution with mouse event
//      this.setOnMouseClicked(event -> {
//          if(event.getClickCount() == 2){
//              combo.getSelectionModel().select(getItem());
//              setText(null);
//              setGraphic(combo);
//              if(!combo.isShowing()){
//                  combo.show();
//              }
//          }
//      });
    }

//  2. Solution with startEdit
    @Override
    public void startEdit() {
        combo.getSelectionModel().select(getItem());
        super.startEdit();
        setText(null);
        setGraphic(combo);
        if(!combo.isShowing()){
            combo.show();
        }
    }

    @Override
    protected void updateItem(S item, boolean empty) {
        super.updateItem(item, empty);
        if(empty){
            setText(null);
            setGraphic(null);
            return;
        }
        setText(getItem().toString());
        setGraphic(null);
    }

    @Override
    public void cancelEdit() {
        super.cancelEdit();
        setText(getItem().toString());
        setGraphic(null);
        if(combo.isShowing()){
            combo.hide();
        }
    }

    @Override
    public void commitEdit(S newValue) {
        super.commitEdit(newValue);
        setGraphic(null);
        setText(getItem().toString());
        if(combo.isShowing()){
            combo.hide();
        }
        setGraphic(null);
        setText(getItem().toString());
    }
}

控制器：

public class Controller implements Initializable {

    @FXML
    private TableView<Model> table;
    @FXML
    private TableColumn<Model,String> col;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        table.setEditable(true);

        col.setCellValueFactory(data -> data.getValue().text);
        col.setCellFactory(factory -> new ComboTableCell<>(Arrays.asList("a","b","c")));

        table.setItems(FXCollections.observableArrayList(Arrays.asList(new Model("a"),new Model("b"))));
    }

     static class Model{

        private StringProperty text;

        public Model(String text) {
            this.text = new SimpleStringProperty(text);
        }

        public String getText() {
            return text.get();
        }

        public StringProperty textProperty() {
            return text;
        }
    }

}

FXML：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TitledPane?>
<AnchorPane xmlns="http://javafx.com/javafx"
            xmlns:fx="http://javafx.com/fxml"
            fx:controller="stackoverflow.combo.Controller">
    <TitledPane text="Table">
        <TableView fx:id="table">
            <columns>
                <TableColumn fx:id="col" prefWidth="200"/>
            </columns>
        </TableView>
    </TitledPane>
</AnchorPane>

我希望可以提供預期結果的任何解決方案，甚至可以建議我使用其他解決方案，該解決方案使用的變通辦法較少或為我建議的“解決方案”之一進行了修復。

JDK版本1.8.0_121

Answer 1

我在使用方法（2）時遇到了同樣的問題，單擊時我的狀態處於以下情況。 出現comboBox，但不會擴展。 進一步單擊將不會觸發任何操作。

最后，我在comboBox上實現了焦點偵聽器，該偵聽器將在焦點顯示時顯示彈出窗口。 我在startEdit的末尾調用了requestFocus 。

// In the creation of comboBox, add focus listener
combo.focusProperty().addListener((observable, oldValue, isFocused) -> if (isFocused) combo.show());

@Override
public void startEdit() {
    combo.getSelectionModel().select(getItem());
    super.startEdit();
    setText(null);
    setGraphic(combo);
    // Creating a JavaFX task to make a small delay and then request focus.
    // Code below is in Kotlin and TornadoFX, but you get the point.
    runAsync {
        Thread.sleep(50)
    } ui {
        combo.requestFocus()
    }
} 

上述延遲是comboBox正確繪制其布局所必需的。 否則，根據布局是否已更新，您將隨機遇到以下情況。

有了這么小的延遲，您將始終保持正確。

PS：如果您在考慮，為什么不只是在短暫延遲后直接調用comboBox.show（）並刪除focusListener？ 好吧，在我的測試中，當您創建新行或調用table.refresh（）時，comboBox只是無法隨機顯示（類似於第一張圖片）。 我想這與virtualFlow和為同一實例創建的tableCell多個實例有關。 看這里 。