选择多行进行排序时发生 JavaFX TreeTableView 异常

Question

我现在正在学习 JavaFX，但我似乎无法做对一件事。基本上我想做的是一个具有多重选择的 TreeTableView，在我尝试对列表进行排序之前它工作得很好。

代码如下(示例 15-1 来自 http://docs.oracle.com/javase/8/javafx/user-interface-tutorial/tree-table-view.htm#CJAEIFDC 的一列 TreeTableView):

import javafx.application.Application;
import javafx.beans.property.ReadOnlyStringWrapper;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableColumn.CellDataFeatures;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableView;
import javafx.stage.Stage;

public class TreeTableViewSample extends Application {

    public static void main(String[] args) {
        Application.launch(args);
    }

    @Override
    public void start(Stage stage) {
        stage.setTitle("Tree Table View Samples");
        final Scene scene = new Scene(new Group(), 200, 400);
        Group sceneRoot = (Group)scene.getRoot();  

        //Creating tree items
        final TreeItem<String> childNode1 = new TreeItem<>("Child Node 1");
        final TreeItem<String> childNode2 = new TreeItem<>("Child Node 2");
        final TreeItem<String> childNode3 = new TreeItem<>("Child Node 3");

        //Creating the root element
        final TreeItem<String> root = new TreeItem<>("Root node");
        root.setExpanded(true);   

        //Adding tree items to the root
        root.getChildren().setAll(childNode1, childNode2, childNode3);        

        //Creating a column
        TreeTableColumn<String,String> column = new TreeTableColumn<>("Column");
        column.setPrefWidth(150);   

        //Defining cell content
        column.setCellValueFactory((CellDataFeatures<String, String> p) -> 
            new ReadOnlyStringWrapper(p.getValue().getValue()));  

        //Creating a tree table view
        final TreeTableView<String> treeTableView = new TreeTableView<>(root);
        TreeTableView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE); //Setting SelectionMode to MULTIPLE
        treeTableView.getColumns().add(column);
        treeTableView.setPrefWidth(152);
        treeTableView.setShowRoot(true);             
        sceneRoot.getChildren().add(treeTableView);
        stage.setScene(scene);
        stage.show();
    }     
}

我添加了这一行:

TreeTableView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE); //Setting SelectionMode to MULTIPLE

一切正常，但当我选择多行并尝试对列进行排序时，仅 Activity 行(最后选择的)保持选中状态。

排序时控制台会给出以下输出:

Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException
    at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.subList(Unknown Source)
    at javafx.collections.ListChangeListener$Change.getAddedSubList(Unknown Source)
    at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.handleSelectedCellsListChangeEvent(Unknown Source)
    at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.access$2100(Unknown Source)
    at javafx.scene.control.TreeTableView.sort(Unknown Source)
    at javafx.scene.control.TreeTableView.doSort(Unknown Source)
    at javafx.scene.control.TreeTableView.lambda$new$115(Unknown Source)
    at javafx.scene.control.TreeTableView$$Lambda$99/1473718685.onChanged(Unknown Source)
    at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(Unknown Source)
    at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(Unknown Source)
    at javafx.collections.ObservableListBase.fireChange(Unknown Source)
    at javafx.collections.ListChangeBuilder.commit(Unknown Source)
    at javafx.collections.ListChangeBuilder.endChange(Unknown Source)
    at javafx.collections.ObservableListBase.endChange(Unknown Source)
    at javafx.collections.ModifiableObservableListBase.setAll(Unknown Source)
    at javafx.collections.ObservableListBase.setAll(Unknown Source)
    at com.sun.javafx.scene.control.skin.TableColumnHeader.sortColumn(Unknown Source)
    at com.sun.javafx.scene.control.skin.TableColumnHeader.lambda$static$55(Unknown Source)
    at com.sun.javafx.scene.control.skin.TableColumnHeader$$Lambda$152/863692449.handle(Unknown Source)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
    at com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source)
    at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
    at javafx.event.Event.fireEvent(Unknown Source)
    at javafx.scene.Scene$MouseHandler.process(Unknown Source)
    at javafx.scene.Scene$MouseHandler.access$1500(Unknown Source)
    at javafx.scene.Scene.impl_processMouseEvent(Unknown Source)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Unknown Source)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$350(Unknown Source)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$224/2145564822.get(Unknown Source)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source)
    at com.sun.glass.ui.View.handleMouseEvent(Unknown Source)
    at com.sun.glass.ui.View.notifyMouse(Unknown Source)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(Unknown Source)
    at com.sun.glass.ui.win.WinApplication$$Lambda$36/2117255219.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

预先感谢您的帮助。

Answer 1

我昨天遇到同样的问题时偶然发现了您的帖子。可惜没有人回复你，我决定自己调查一下。令人难以置信的是，如此常见的功能中的错误可能多年来都没有被注意到和修复......

因为在我看来，它就像 JavaFX 中 TreeTableView.TreeTableViewArrayListSelectionModel 中的错误。有一个处理程序可以更新选择以响应数据模型中的更改:

        private EventHandler<TreeItem.TreeModificationEvent<S>> treeItemListener = new EventHandler<TreeItem.TreeModificationEvent<S>>() {
        @Override public void handle(TreeItem.TreeModificationEvent<S> e) {

            if (getSelectedIndex() == -1 && getSelectedItem() == null) return;
            <...>

在某个时刻(第 2421 行)它处理排序情况(即排列):

               } else if (e.wasPermutated()) {
                // This handles the sorting case where nothing was added or
                // removed, but the location of the selected index / item
                // has likely changed. This was added to fix RT-30156 and
                // unit tests exist to prevent it from regressing.
                quietClearSelection();
                select(oldSelectedItem);
            } else if (e.wasAdded()) {

此代码尝试根据其内容(而不是排序期间可能更改的行号)重新选择正确的项目。但不幸的是它没有考虑多选的情况，排序后只留下一项被选中。

发生崩溃(异常)是因为 TreeTableView 的 sort() 方法似乎解决了相同的问题(排序完成后恢复正确的选择)，通过保存排序前后的选择索引，并发出排列事件:

    final List<TreeTablePosition<S,?>> prevState = new ArrayList<>(getSelectionModel().getSelectedCells());
    final int itemCount = prevState.size();

    <...>

            final TreeTableViewArrayListSelectionModel<S> sm = (TreeTableViewArrayListSelectionModel<S>) getSelectionModel();
            final ObservableList<TreeTablePosition<S, ?>> newState = sm.getSelectedCells();

            List<TreeTablePosition<S, ?>> removed = new ArrayList<>();
            for (int i = 0; i < itemCount; i++) {
                TreeTablePosition<S, ?> prevItem = prevState.get(i);
                if (!newState.contains(prevItem)) {
                    removed.add(prevItem);
                }
            }

            if (!removed.isEmpty()) {
                // the sort operation effectively permutates the selectedCells list,
                // but we cannot fire a permutation event as we are talking about
                // TreeTablePosition's changing (which may reside in the same list
                // position before and after the sort). Therefore, we need to fire
                // a single add/remove event to cover the added and removed positions.
                ListChangeListener.Change<TreeTablePosition<S, ?>> c = new NonIterableChange.GenericAddRemoveChange<>(0, itemCount, removed, newState);
                sm.handleSelectedCellsListChangeEvent(c);
            }

在最后一行之前，创建 onIterableChange.GenericAddRemoveChange 对象，同时假设 newState 列表具有 itemCount 元素(而 >newState 将始终包含 1 个元素，如上所述)，并且在尝试从中获取 itemCount 元素时会崩溃。

现在，你能做些什么呢？要彻底修复它，您需要:

1. 子类化TreeTableView并重写sort()方法，或者
2. 使用 TreeTableView.SetSelectionModel() 提供您自己的 SelectionModel 实现(可能基于 TreeTableViewArrayListSelectionModel 实现)

这两种方法都不简单，因为代码大量使用可私有(private)访问的成员。使用第一个解决方案，您还将面临 FXMLLoader 的问题，它只能创建 TreeTableView (而不是您的子类 MyTreeTableView)，但是您应该能够手动创建该对象。

我想我会坚持以下解决方法，每当表格排序时清除选择(在我的情况下不会发生很多):

 myTreeTable.setOnSort(event -> { 
     if(myTreeTable.getSelectionModel().getSelectedIndices().size() > 1) 
         myTreeTable.getSelectionModel().clearSelection(); 
 });

希望这有帮助!