JavaFX：单击 CheckBoxTreeItem 时获取所选值

Question

我想获取TreeView包含 CheckBoxTreeItems 中的所有选定值。

如何做到这一点？

Answer 1

您可以侦听根目录上的事件以保持Set<TreeItem>最新状态，或者您可以从根目录开始对所选项目执行 DFS。

请注意，DFS 方法当然需要较少量的代码，但另一种方法允许您在修改期间保持设置最新...

@Override
public void start(Stage primaryStage) {
    CheckBoxTreeItem<String> root = new CheckBoxTreeItem<>("root");
    CheckBoxTreeItem<String> c1 = new CheckBoxTreeItem<>("c1");
    c1.getChildren().addAll(
            new CheckBoxTreeItem<>("c1.1"),
            new CheckBoxTreeItem<>("c1.2"),
            new CheckBoxTreeItem<>("c1.3")
    );
    CheckBoxTreeItem<String> c2 = new CheckBoxTreeItem<>("c2");
    c2.getChildren().addAll(
            new CheckBoxTreeItem<>("c2.1"),
            new CheckBoxTreeItem<>("c2.2"),
            new CheckBoxTreeItem<>("c2.3")
    );
    CheckBoxTreeItem<String> c3 = new CheckBoxTreeItem<>("c3");
    c3.getChildren().addAll(
            new CheckBoxTreeItem<>("c3.1"),
            new CheckBoxTreeItem<>("c3.2"),
            new CheckBoxTreeItem<>("c3.3")
    );
    root.getChildren().addAll(c1, c2, c3);

    TreeView<String> treeView = new TreeView<>(root);
    treeView.setCellFactory(CheckBoxTreeCell.forTreeView());
    Set<TreeItem<String>> selected = new HashSet<>();

    // listen for selection change
    root.addEventHandler(CheckBoxTreeItem.checkBoxSelectionChangedEvent(), (CheckBoxTreeItem.TreeModificationEvent<String> evt) -> {
        CheckBoxTreeItem<String> item = evt.getTreeItem();

        if (evt.wasIndeterminateChanged()) {
            if (item.isIndeterminate()) {
                selected.remove(item);
            } else if (item.isSelected()) {
                selected.add(item);
            }
        } else if (evt.wasSelectionChanged()) {
            if (item.isSelected()) {
                selected.add(item);
            } else {
                selected.remove(item);
            }
        }
    });

    // listen for subtree add/remove
    root.addEventHandler(TreeItem.childrenModificationEvent(), (TreeItem.TreeModificationEvent<String> evt) -> {
        if (evt.wasAdded()) {
            for (TreeItem<String> added : evt.getAddedChildren()) {
                addSubtree(selected, (CheckBoxTreeItem<String>) added);
            }
        }
        if (evt.wasRemoved()) {
            for (TreeItem<String> removed : evt.getRemovedChildren()) {
                removeSubtree(selected, (CheckBoxTreeItem<String>) removed);
            }
        }
    });

    Button button = new Button("print selected");
    button.setOnAction(evt -> {
        System.out.println("----------------");
        selected.stream().map(TreeItem::getValue).forEach(System.out::println);
    });

    Button button2 = new Button("print dfs");
    button2.setOnAction(evt -> {
        System.out.println("----------------");
        print(root);
    });

    Button remove = new Button("remove");
    remove.setOnAction(evt -> {
        root.getChildren().remove(c3);
    });

    Scene scene = new Scene(new VBox(treeView, button, button2, remove));

    primaryStage.setScene(scene);
    primaryStage.show();
}

private static <T> void removeSubtree(Collection<TreeItem<T>> collection, CheckBoxTreeItem<T> item) {
    if (item.isSelected()) {
        collection.remove(item);
    } else if (!item.isIndeterminate() && !item.isIndependent()) {
        return;
    }
    for (TreeItem<T> child : item.getChildren()) {
        removeSubtree(collection, (CheckBoxTreeItem<T>) child);
    }
}

private static <T> void addSubtree(Collection<TreeItem<T>> collection, CheckBoxTreeItem<T> item) {
    if (item.isSelected()) {
        collection.add(item);
    } else if (!item.isIndeterminate() && !item.isIndependent()) {
        return;
    }
    for (TreeItem<T> child : item.getChildren()) {
        addSubtree(collection, (CheckBoxTreeItem<T>) child);
    }
}

private static <T> void print(CheckBoxTreeItem<T> item) {
    if (item.isSelected()) {
        System.out.println(item.getValue());
    } else if (!item.isIndeterminate() && !item.isIndependent()) {
        return;
    }
    for (TreeItem<T> child : item.getChildren()) {
        print((CheckBoxTreeItem<T>) child);
    }
}