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JavaFX TreeView

Jakob Jenkov
Last update: 2019-03-17

The JavaFX TreeeView enables you to display tree views inside your JavaFX applications. The JavaFX TreeView is represented by the class javafx.scene.control.TreeView . Here is a screenshot of a JavaFX TreeView:

A JavaFX TreeView screenshot

Create a TreeView

You create a JavaFX TreeView simply by creating a new instance of the TreeView class. Here is an example of creating a new JavaFX TreeView instance:

TreeView treeView = new TreeView();

Add TreeView to Scene Graph

To make a JavaFX TreeView visible it must be added to the JavaFX scene graph. Here is an example showing how to add a JavaFX TreeView to the JavaFX scene graph:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class TreeViewExample extends Application {

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

    @Override
    public void start(Stage primaryStage) {
        TreeView treeView = new TreeView();

        VBox vbox = new VBox(treeView);

        Scene scene = new Scene(vbox);

        primaryStage.setScene(scene);

        primaryStage.show();
    }

}

Notice, that the TreeView created in the above example will not have any items (nodes) to display. We will see how to add tree items to a TreeView in the next section.

Add Tree Items to TreeView

The items in the tree displayed by a JavaFX TreeView are represented by the TreeItem class (javafx.scene.control.TreeItem). Here is an example of creating a set of TreeItem instances and adding them to a JavaFX TreeView instance:

TreeItem rootItem = new TreeItem("Tutorials");

TreeItem webItem = new TreeItem("Web Tutorials");
webItem.getChildren().add(new TreeItem("HTML  Tutorial"));
webItem.getChildren().add(new TreeItem("HTML5 Tutorial"));
webItem.getChildren().add(new TreeItem("CSS Tutorial"));
webItem.getChildren().add(new TreeItem("SVG Tutorial"));
rootItem.getChildren().add(webItem);

TreeItem javaItem = new TreeItem("Java Tutorials");
javaItem.getChildren().add(new TreeItem("Java Language"));
javaItem.getChildren().add(new TreeItem("Java Collections"));
javaItem.getChildren().add(new TreeItem("Java Concurrency"));
rootItem.getChildren().add(javaItem);

TreeView treeView = new TreeView();
treeView.setRoot(rootItem);

Add Children to a TreeItem

If you look at the example in the previous section, you can see that a TreeItem can have other TreeItem instances as children. This parent-child relationship can continue recursively, indefinitely. This is how you structure the tree nodes logically in your JavaFX application. Here is an example that shows how to add child TreeItem instances to a parent TreeItem:

TreeItem javaItem = new TreeItem("Java Tutorials");
javaItem.getChildren().add(new TreeItem("Java Language"));
javaItem.getChildren().add(new TreeItem("Java Collections"));
javaItem.getChildren().add(new TreeItem("Java Concurrency"));

TreeItem rootItem = new TreeItem("Tutorials");
rootItem.getChildren().add(javaItem);

This example creates a tree with a single root TreeItem which has one child TreeItem set on it, and this child TreeItem has itself 3 child TreeItem instances added to it.

Hide Root Item of TreeView

You can hide the root item (root node) of a JavaFX TreeView. You do so by calling the setShowRoot() method, passing the boolean value false to it as parameter. Here is an example of hiding the root TreeItem of a JavaFX TreeView:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class TreeViewExample extends Application {

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

    @Override
    public void start(Stage primaryStage) {


        TreeItem rootItem = new TreeItem("Tutorials");

        TreeItem webItem = new TreeItem("Web Tutorials");
        webItem.getChildren().add(new TreeItem("HTML  Tutorial"));
        webItem.getChildren().add(new TreeItem("HTML5 Tutorial"));
        webItem.getChildren().add(new TreeItem("CSS Tutorial"));
        webItem.getChildren().add(new TreeItem("SVG Tutorial"));
        rootItem.getChildren().add(webItem);

        TreeItem javaItem = new TreeItem("Java Tutorials");
        javaItem.getChildren().add(new TreeItem("Java Language"));
        javaItem.getChildren().add(new TreeItem("Java Collections"));
        javaItem.getChildren().add(new TreeItem("Java Concurrency"));
        rootItem.getChildren().add(javaItem);

        TreeView treeView = new TreeView();
        treeView.setRoot(rootItem);

        treeView.setShowRoot(false);


        VBox vbox = new VBox(treeView);

        Scene scene = new Scene(vbox);

        primaryStage.setScene(scene);

        primaryStage.show();
    }

}

Notice the line in bold. That is the line that instructs the JavaFX TreeView to hide the root node. Here is a screenshot showing how the resulting JavaFX TreeView looks, with all nodes expanded:

A JavaFX TreeView that hides its root TreeItem

Notice how the root TreeItem with the text Tutorials is not displayed.

Jakob Jenkov




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