我扩展了SimpleObjectProperty<T>以创建自定义的延迟加载实现(请参阅此处(，LazyLoadingObjectProperty<T> 。
要将此通用实现用于布尔属性，我使用 LazyLoadingObjectProperty<Boolean> .
在我的表中，我想将布尔属性呈现为CheckBox。
尽管如此， CheckBoxTableCell似乎只适用于BooleanProperty，而不适用于ObjectProperty<Boolean>。
为什么会这样，我该如何解决方法？
下面是一些代码：
public class ExampleTable extends Application {
private static final int NUM_ELEMENTS = 5000;
private final TableView<ExampleBean> table = new TableView<>();
private final ObservableList<ExampleBean> data = FXCollections.observableArrayList();
public static void main(final String[] args) {
launch(args);
}
@Override
public void start(final Stage stage) {
final Scene scene = new Scene(new Group());
stage.setTitle("Table View Sample");
stage.setWidth(300);
stage.setHeight(500);
final TableColumn<ExampleBean, Boolean> c1 = new TableColumn<>("A");
c1.setCellValueFactory(new PropertyValueFactory<ExampleBean, Boolean>("p1"));
c1.setCellFactory(CheckBoxTableCell.forTableColumn(c1));
c1.setEditable(true);
c1.setPrefWidth(100);
final TableColumn<ExampleBean, String> c2 = new TableColumn<>("B");
c2.setCellValueFactory(new PropertyValueFactory<ExampleBean, String>("p2"));
c2.setCellFactory(TextFieldTableCell.forTableColumn());
c2.setEditable(true);
c2.setPrefWidth(100);
for (int i = 0; i < NUM_ELEMENTS; i++) {
data.add(new ExampleBean());
}
final ScrollPane sp = new ScrollPane();
sp.setContent(table);
sp.setMaxHeight(Double.POSITIVE_INFINITY);
sp.setMaxWidth(Double.POSITIVE_INFINITY);
sp.setFitToHeight(true);
sp.setFitToWidth(true);
table.setEditable(true);
table.setItems(data);
// table.setMaxHeight(Double.POSITIVE_INFINITY);
// table.setMaxWidth(Double.POSITIVE_INFINITY);
table.getColumns().addAll(c1, c2);
final ContextMenu cm = new ContextMenu();
cm.getItems().add(new MenuItem("bu"));
table.setContextMenu(cm);
final VBox vbox = new VBox();
vbox.setSpacing(5);
VBox.setVgrow(sp, Priority.ALWAYS);
vbox.getChildren().addAll(sp);
scene.setRoot(vbox);
stage.setScene(scene);
stage.show();
}
}
public class ExampleBean {
private ObjectProperty<Boolean> p1;
private ObjectProperty<String> p2;
public ExampleBean() {
p1 = new SimpleObjectProperty(true);
p1.addListener((o, ov, nv) -> {
System.err.println("Value changed " + ov + " -> " + nv);
});
p2 = new SimpleObjectProperty(Integer.toString(new Random().nextInt()));
p2.addListener((o, ov, nv) -> {
System.err.println("Value changed " + ov + " -> " + nv);
});
}
public final ObjectProperty<Boolean> p1Property() {
return this.p1;
}
public final ObjectProperty<String> p2Property() {
return this.p2;
}
}
请注意，该属性使用 Boolean.TRUE 初始化，并且不选中复选框单元格。
此问题未使用/不需要：
public abstract class LazyLoadingObjectProperty<T> extends SimpleObjectProperty<T> {
public LazyLoadingObjectProperty() {
super();
}
public LazyLoadingObjectProperty(final Object bean, final String name, final T initialValue) {
super(bean, name, initialValue);
}
public LazyLoadingObjectProperty(final Object bean, final String name) {
super(bean, name);
}
public LazyLoadingObjectProperty(final T initialValue) {
super(initialValue);
}
private boolean loaded = false;
private final ChangeListener<T> valueChangeListener = (o, ov, nv) -> {
valueExternallyUpdated(nv);
};
/**
* Is called after the background task's finished (success or failure). Override
* if needed. E.g. to bind the value afterwards.
*/
protected void afterLoaded() {
addListener(valueChangeListener);
}
/**
* Returns a {@link Task} that will calculate this Property's value in the
* background.
*
* @return a {@link Task} that will calculate this Property's value in the
* background.
*/
protected abstract Task<T> createTask();
protected T getFailedValue(final Throwable t) {
return null;
}
@Override
public T getValue() {
if (!loaded) {
startLoadingService();
}
return super.getValue();
}
public boolean isLoaded() {
return loaded;
}
public void setLoaded(final boolean loaded) {
// the loaded property has been reset manually. Remove change listener
if (this.loaded && !loaded) {
removeListener(valueChangeListener);
}
this.loaded = loaded;
}
@Override
public void setValue(final T v) {
super.setValue(v);
}
/**
* Starts the {@link Task} that will calculate this Property's value in the
* background.
*/
protected void startLoadingService() {
setLoaded(true);
final Task<T> s = LazyLoadingObjectProperty.this.createTask();
LazyLoadingThreads.getExecutorService().submit(s);
s.setOnFailed(e -> {
setValue(getFailedValue(e.getSource().getException()));
afterLoaded();
});
s.setOnSucceeded(e -> {
setValue(s.getValue());
afterLoaded();
});
}
/**
* Override this callback method to handle external value-change-events
* (not-lazily-loaded). This callback is only called, if the value is updated
* manually, i.e., not via the lazy-loading mechanism.
*
* @param nv
* the new value
*/
protected void valueExternallyUpdated(final T nv) {
// override if needed
}
}
在这里找到mwe。
至少在文档中，但在实现中绝对是一个错误：选中的复选框和索引处的可观察值之间的自动双向绑定 - 如果可能的话 - 是设计意图。即使可以，实施也未能满足这一要求。
快速黑客是一个自定义子类，用于修复错误，例如(未正式测试，当心！
public static class FixedCheckBoxTableCell<S, T> extends CheckBoxTableCell<S, T> {
@Override
public void updateItem(T item, boolean empty) {
checkCallback();
super.updateItem(item, empty);
}
private void checkCallback() {
if (getSelectedStateCallback() != null) return;
ObservableValue<Boolean> observable =
(ObservableValue<Boolean>) getTableColumn().getCellObservableValue(getIndex());
// handled by super
if (observable instanceof BooleanProperty) return;
// can't bidi-bind anyway
if (!(observable instanceof Property)) return;
// getting here if we have a ObjectProperty<Boolean>, that's not handled by super
setSelectedStateCallback(index -> {
ObjectProperty<Boolean> p = (ObjectProperty<Boolean>) getTableColumn().getCellObservableValue(index);
return BooleanProperty.booleanProperty(p);
});
}
}