我目前收到一个我不明白的错误。抛出的异常在我的代码中没有任何意义，但只有在我通过清除根项的子项并为其添加新的 och 子项来重新填充 TreeTableView 后才会抛出该异常。
这是一个例外：
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.handleSelectedCellsListChangeEvent(TreeTableView.java:3056)
at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.clearAndSelect(TreeTableView.java:2527)
at com.sun.javafx.scene.control.behavior.TableCellBehaviorBase.simpleSelect(TableCellBehaviorBase.java:209)
at com.sun.javafx.scene.control.behavior.TableCellBehaviorBase.doSelect(TableCellBehaviorBase.java:148)
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:132)
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.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$MouseHandler.process(Scene.java:3724)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3452)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1728)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2461)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:348)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:273)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:382)
at com.sun.glass.ui.View.handleMouseEvent(View.java:553)
at com.sun.glass.ui.View.notifyMouse(View.java:925)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$141(WinApplication.java:102)
at com.sun.glass.ui.win.WinApplication$$Lambda$37/1798286609.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
一个小的 MCVE（按“-”以重新填充 TreeTableView，然后编辑一个单元格以获取异常）：
package test;
import javafx.application.Application;
import javafx.beans.value.ObservableValue;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.TitledPane;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableColumn.CellDataFeatures;
import javafx.scene.control.TreeTableColumn.CellEditEvent;
import javafx.scene.control.TreeTableView;
import javafx.scene.control.cell.TextFieldTreeTableCell;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.stage.Stage;
import javafx.util.Callback;
public class BillingTableTest extends Application {
private Stage stage;
private Scene scene;
private TitledPane pane;
private TreeTableView<String> table;
private TreeItem<String> root;
/**
* Start the program from scratch.
*
* @param args
* Input arguments. Leave empty.
*/
public static void main(String[] args) {
launch(args);
}
/**
* Start the program. Not usually called by the user, but by JavaFX. Nothing
* fancy here, but setting up a basic TreeTableView with one column.
*/
public void start(Stage stage) {
this.stage = stage;
pane = new TitledPane();
scene = new Scene(pane);
pane.setOnKeyReleased(new EventHandler<KeyEvent>() {
@Override
public void handle(KeyEvent event) {
// TODO Auto-generated method stub
if (event.getCode() == KeyCode.SUBTRACT) {
repopulate();
}
}
});
table = new TreeTableView<>();
root = new TreeItem<>("Root");
root.setExpanded(true);
table.setRoot(root);
table.setShowRoot(false);
table.setEditable(true);
TreeTableColumn<String, String> column = new TreeTableColumn<String, String>("String");
column.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<String, String>, ObservableValue<String>>() {
@Override
public ObservableValue<String> call(CellDataFeatures<String, String> param) {
// TODO Auto-generated method stub
return param.getValue().valueProperty();
}
});
column.setCellFactory(TextFieldTreeTableCell.forTreeTableColumn());
column.setOnEditCommit(new EventHandler<TreeTableColumn.CellEditEvent<String, String>>() {
@Override
public void handle(CellEditEvent<String, String> t) {
t.getTreeTablePosition().getTreeItem().setValue(t.getNewValue());
}
});
table.getColumns().add(column);
populate();
pane.setContent(table);
stage.setScene(scene);
stage.show();
System.out.println("TreeTableView has not been repopulated. Editing will not throw an exception.");
System.out.println("Press - to repopulate it and break it.");
}
/**
* Populate the TreeTableView with some dummy data.
*/
private void populate() {
for (int i = 1; i <= 10; i++) {
String string = "String " + i;
TreeItem<String> treeItem = new TreeItem<String>(string);
root.getChildren().add(treeItem);
}
}
/**
* Clear root children (clears the TreeTableView). Cell editing is most
* likely broken by this.
*/
private void clear() {
root.getChildren().clear(); // <- Most likely the problem.
}
/**
* Repopulate the root node (repopulate the TreeTableView). After this
* method is called, cell editing will throw an excetion.
*/
private void repopulate() {
clear(); // <- Most likely the problem.
populate();
System.out.println("TreeTableView has been repopulated. Editing will now throw an exception");
}
}
我知道该错误与选择 TreeTableCells 有关，并且在第一次重新填充表格后选择一个时发生。否则，在重新填充之前，一切都会按预期工作，并且不会抛出任何异常。
问题是什么？您是否不允许清除 TreeTableRoow 中的子 ObservableList，还是应该以其他方式完成？