AnchorPane

AnchorPane is a layout container in JavaFX that lets you position elements by attaching them to the edges of the pane: top, bottom, left, and right.

This is useful when you want a control to stay in a fixed position even if the window is resized.

Example:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;

public class AnchorPaneExample extends Application {

    @Override
    public void start(Stage stage) {

        Button topLeftButton = new Button("Top Left");
        Button bottomRightButton = new Button("Bottom Right");

        AnchorPane root = new AnchorPane();

        root.getChildren().addAll(topLeftButton, bottomRightButton);

        // Attach the first button 10px from the top and left
        AnchorPane.setTopAnchor(topLeftButton, 10.0);
        AnchorPane.setLeftAnchor(topLeftButton, 10.0);

        // Attach the second button 10px from the bottom and right
        AnchorPane.setBottomAnchor(bottomRightButton, 10.0);
        AnchorPane.setRightAnchor(bottomRightButton, 10.0);

        Scene scene = new Scene(root, 400, 300);

        stage.setTitle("AnchorPane Example");
        stage.setScene(scene);
        stage.show();
    }

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

What happens:

• topLeftButton always stays 10 pixels from the top-left corner.
• bottomRightButton always stays 10 pixels from the bottom-right corner.
• If the window becomes larger or smaller, the buttons keep those distances.

You can also anchor an element on both left and right sides so it stretches:

TextField textField = new TextField();

root.getChildren().add(textField);

AnchorPane.setTopAnchor(textField, 20.0);
AnchorPane.setLeftAnchor(textField, 20.0);
AnchorPane.setRightAnchor(textField, 20.0);

Now the TextField will grow and shrink horizontally when the window is resized.

FXML version:

<AnchorPane prefWidth="400" prefHeight="300"
            xmlns:fx="http://javafx.com/fxml">

    <children>
        <Button text="Top Left"
                AnchorPane.topAnchor="10.0"
                AnchorPane.leftAnchor="10.0"/>

        <Button text="Bottom Right"
                AnchorPane.bottomAnchor="10.0"
                AnchorPane.rightAnchor="10.0"/>
    </children>
</AnchorPane>

Common anchor methods:

AnchorPane.setTopAnchor(node, 10.0);
AnchorPane.setBottomAnchor(node, 10.0);
AnchorPane.setLeftAnchor(node, 10.0);
AnchorPane.setRightAnchor(node, 10.0);

A node can have:

• only top + left
• only bottom + right
• left + right (stretch horizontally)
• top + bottom (stretch vertically)
• all four (stretch in both directions)

For example, to make a ListView fill almost the whole window:

AnchorPane.setTopAnchor(listView, 10.0);
AnchorPane.setBottomAnchor(listView, 10.0);
AnchorPane.setLeftAnchor(listView, 10.0);
AnchorPane.setRightAnchor(listView, 10.0);