展开/折叠时，JavaFX CheckBoxTreeItem图形消失/出现

Question

I'm trying to make TreeView with CheckBoxTreeItems. When I collapse/expand a CheckBoxTreeItems the image I set up does not display correctly. I googled but I couldn't find correct answer. On Stack Overflow, I found a similar problem, but I didn't get a valid answer.

Eg

JavaFX CheckBoxTreeItem graphic disappear when siblings collapse

JavaFX CheckBoxTreeItem: Graphic disappears if graph is extended

Any ideas?

public class ClientApplication extends Application {

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

    @Override
    public void start(final Stage stage) {
        ImageView folderIcon = new ImageView();
        Image folderImage = new Image("image/folder.png");
        folderIcon.setImage(folderImage);
        folderIcon.setFitWidth(16);
        folderIcon.setFitHeight(16);
        CheckBoxTreeItem<String> rootItem = new CheckBoxTreeItem<String>("folder", folderIcon);
        rootItem.setExpanded(true);

        for (int i = 0; i < 4; i++) {
            CheckBoxTreeItem<String> checkBoxTreeItem = new CheckBoxTreeItem<String>("Sample" + (i + 1), folderIcon);
            rootItem.getChildren().add(checkBoxTreeItem);
        }

        final TreeView<String> tree = new TreeView<String>(rootItem);
        tree.setCellFactory(CheckBoxTreeCell.<String>forTreeView());
        tree.setRoot(rootItem);
        tree.setShowRoot(true);


        StackPane root = new StackPane();
        root.getChildren().add(tree);
        stage.setScene(new Scene(root, 300, 250));
        stage.show();
    }
}

enter image description here

I tried to use the ideas provided by @Jai,But when I click the expand/collapse icon, there is still a problem.Attachment is a screenshot.Thanks in advance.

enter image description here

Answer 1

ImageView is a JavaFX control. This means that each instance represents a unique control you see on your screen. You should never use the same instance for multiple locations in your GUI.

On the other hand, Image represents an image (ie an array of pixel data), so it is reusable.

This should work:

@Override
public void start(final Stage stage) {
    final Image folderImage = new Image("image/folder.png");

    CheckBoxTreeItem<String> rootItem = new CheckBoxTreeItem<String>("folder", createImageView(folderImage));
    rootItem.setExpanded(true);

    for (int i = 0; i < 4; i++) {
        CheckBoxTreeItem<String> checkBoxTreeItem = new CheckBoxTreeItem<String>("Sample" + (i + 1), createImageView(folderImage));
        rootItem.getChildren().add(checkBoxTreeItem);
    }

    final TreeView<String> tree = new TreeView<String>(rootItem);
    tree.setCellFactory(CheckBoxTreeCell.<String>forTreeView());
    tree.setRoot(rootItem);
    tree.setShowRoot(true);


    StackPane root = new StackPane();
    root.getChildren().add(tree);
    stage.setScene(new Scene(root, 300, 250));
    stage.show();
}

private ImageView createImageView(Image folderImage) {
    ImageView folderIcon = new ImageView();
    folderIcon.setImage(folderImage);
    folderIcon.setFitWidth(16);
    folderIcon.setFitHeight(16);

    return folderIcon;
}