GroupVsPaneDemo.java

A Group is not resizable (meaning that its size is not managed by its parent in the scene graph), and takes on the union of the bounds of its child nodes. (So, in other words, the local bounds of a Group will be the smallest rectangle containing the bounds of all the child nodes). If it is larger than the space it is allocated in its parent, it will be clipped.

By contrast, a Pane is resizable, so its size is set by its parent, which essentially determine its bounds.

javafx.scene.Node javafx.scene.Parent javafx.scene.Group	javafx.scene.Node javafx.scene.Parent javafx.scene.layout.Region javafx.scene.layout.Pane
Group	Pane

Here is a quick demo. The Group is on top and the Pane below. Both contain a fixed blue square at (100,100) and a green square which is moved by pressing the left/right arrow keys. The green rectangles (rect3 and rect3) are moved by the following statements:

     rect3.setX(rect3.getX() + deltaX);
     rect4.setX(rect4.getX() + deltaX);

Note how at the beginning, the blue square appears in the top left corner of the group, because the local bounds of the group start at the top-leftmost point of all its child nodes (i.e. the local bounds of the group extend from (100, 100) right and down). As you move the green rectangles "off screen", the group adjusts its bounds to incorporate the changes, wherever possible, whereas the pane remains fixed. Note that the bottom blue square, belonging to the pane, never moves.

The few important difference between Pane and Group is that :

• Pane can have its own size, where as a Group will take on the collective bounds of its children and is not directly resizable.
• Pane can be used when you want to position its nodes at absolute position.

Reference: Group vs. Pane from stackoverflow.com

GroupVsPaneDemo.java

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.Pane;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class GroupVsPaneDemo extends Application {

    @Override
    public void start(Stage primaryStage) {
        Pane pane = new Pane();
        Group group = new Group();

        VBox.setVgrow(group, Priority.NEVER);
        VBox.setVgrow(pane, Priority.NEVER);

        VBox vbox = new VBox(group, pane);


        Rectangle rect1 = new Rectangle(100, 100, 100, 100);
        Rectangle rect2 = new Rectangle(100, 100, 100, 100);
        Rectangle rect3 = new Rectangle(200, 200, 100, 100);
        Rectangle rect4 = new Rectangle(200, 200, 100, 100);
        rect1.setFill(Color.BLUE);
        rect2.setFill(Color.BLUE);
        rect3.setFill(Color.GREEN);
        rect4.setFill(Color.GREEN);

        group.getChildren().addAll(rect1, rect3);
        pane.getChildren().addAll(rect2, rect4);

        Scene scene = new Scene(vbox, 800, 800);
        scene.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
            double deltaX ;
            switch(e.getCode()) {
                case LEFT:
                    deltaX = -10 ;
                    break ;
                case RIGHT:
                    deltaX = 10 ;
                    break ;
                default:
                    deltaX = 0 ;
            }
            rect3.setX(rect3.getX() + deltaX);
            rect4.setX(rect4.getX() + deltaX);
        });

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

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

Maintained by John Loomis, updated Fri Jan 26 12:53:36 2018