JavaFx:TreeTableView奇怪的NullpointerException

我注意到

TreeTableView

如果在没有行的表中双击，就会发生这种情况。我会附上一个截图来显示我的确切意思

我完全来自JavaFx，它与我的代码无关。我也做了一项研究，没有发现任何与此相关的东西

下面是一个简单的代码来重现它：

控制器：

public class Controller implements Initializable {
    @FXML
    private TreeTableColumn<Model, String> column;
    @FXML
    private TreeTableView<Model> treeTable;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        TreeItem<Model> root = new TreeItem<>(new Model("Root"));
        treeTable.setRoot(root);
        column.setCellValueFactory(value -> value.getValue().getValue().textProperty());

    }

    private class Model {
        private StringProperty text;

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

        public StringProperty textProperty() {
            return text;
        }

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

        @Override
        public String toString() {
            return getText();
        }
    }
}

Java版本：1.8u121

---

作为一个解决方案，我会接受任何真正有效的解决方法，或者任何解释/javafx错误报告，表明他们正在解决它，或者在下面的版本中有一个修复程序

当您在没有列的空白处单击时，您最终会单击一个

TreeTableRow

。显然，控件的行为类中有一个bug，这意味着它无法处理带有

null

项的行。如果在列的空白处单击，则不会看到此错误，因为单击的是

TreeTableCell

，其行为类似乎没有遇到相同的问题。不确定确切的区别在哪里，但我只是快速浏览了一下源代码

正如@kleopatra所提到的，停止抛出异常的一种方法是在

TreeTableRow

中添加一个事件过滤器，该过滤器会在空行上双击

var table = new TreeTableView<String>();
table.setRowFactory(ttv -> {
    var row = new TreeTableRow<String>();
    row.addEventFilter(MouseEvent.MOUSE_PRESSED, event -> {
        if (row.getItem() == null && event.getClickCount() % 2 == 0) {
            event.consume();
        }
    });
    return row;
});

var table=new TreeTableView（）；
表.setRowFactory（ttv->{
var row=新的TreeTableRow（）；
row.addEventFilter（MouseEvent.MOUSE_按下，事件->{
if（row.getItem（）==null&&event.getClickCount（）%2==0）{
event.consume（）；
}
});
返回行；
});

---

注意：您需要

clickCount%2==0

，因为当单击计数为偶数时，行为类将尝试访问

TreeItem

。

好的，一个非常糟糕的解决方法是简单地捕获异常并处理它。这是treeTableRowBehavior.handleClicks中的一个错误（见fx11）-代码无法处理空行。。您可以考虑报告：）作为一个黑客，您可能尝试在一个自定义行上登记一个EVENTFECT，如果它是一个事件，那么它将消耗一个事件。doubleClick@kleopatra我试过了，但还是一样的NPE。你的意思是：？注意你可以提交一个bug报告。哇，谢谢你的解释和答案：）你会建议报告它吗？是的，当然-开发团队不知道的bug很少被修复：）顺便说一句，这种黑客有一个缺点：由于是一个过滤器，双击将永远不会到达空的treeTableCell，因此定制的cell实现无法对空单元格进行任何处理。我的猜测是，这是相当罕见的，但应该记住谢谢你的报道：）

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at com.sun.javafx.scene.control.behavior.TreeTableRowBehavior.handleClicks(TreeTableRowBehavior.java:89)
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.simpleSelect(CellBehaviorBase.java:259)
    at com.sun.javafx.scene.control.behavior.TableRowBehaviorBase.doSelect(TableRowBehaviorBase.java:120)
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:150)
    at com.sun.javafx.scene.control.behavior.TableRowBehaviorBase.mousePressed(TableRowBehaviorBase.java:64)
    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.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)

var table = new TreeTableView<String>();
table.setRowFactory(ttv -> {
    var row = new TreeTableRow<String>();
    row.addEventFilter(MouseEvent.MOUSE_PRESSED, event -> {
        if (row.getItem() == null && event.getClickCount() % 2 == 0) {
            event.consume();
        }
    });
    return row;
});