Experiment with creating a reusable ExpandableTextArea that grows/shrinks according to the text inside it. This is a bit of a hack: uses a lookup and an AnimationTimer to execute the lookup when the css styles have been applied.

ExpandableTextArea.java

package expandabletextarea;

import java.util.concurrent.Callable;

import javafx.animation.AnimationTimer;
import javafx.beans.binding.Bindings;
import javafx.scene.Node;
import javafx.scene.control.TextArea;

public class ExpandableTextArea extends TextArea {
	public ExpandableTextArea(String text) {
		super(text);
		setMinHeight(24);
		new AnimationTimer() {
			@Override
			public void handle(long now) {
				Node text = lookup(".text");
				if (text != null) {
					prefHeightProperty().bind(
						Bindings.createDoubleBinding(
							new Callable<Double>() {
								@Override
								public Double call() throws Exception {
									return text.getBoundsInLocal().getHeight();
								}
							}, text.boundsInLocalProperty()).add(20));
					this.stop();
				}
			}
		}.start();
	}
	public ExpandableTextArea() {
		this("");
	}
}

ExpandableTextAreaTest.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.control.Tab?>
<?import expandabletextarea.ExpandableTextArea?>

<BorderPane xmlns:fx="http://javafx.com/fxml">
	<center>
		<TabPane>
			<tabs>
				<Tab text="Tab 1">
					<content>
						<VBox>
							<ExpandableTextArea text="Text area 1" />
						</VBox>
					</content>
				</Tab>
				<Tab text="Tab 2">
					<content>
						<VBox>
							<ExpandableTextArea text="Text area 2" />
						</VBox>
					</content>
				</Tab>
				<Tab text="Tab 3">
					<content>
						<VBox>
							<ExpandableTextArea text="Text area 3" />
						</VBox>
					</content>
				</Tab>
			</tabs>
		</TabPane>
	</center>
</BorderPane>

Main.java

package expandabletextarea;
	
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;

public class Main extends Application {
	@Override
	public void start(Stage primaryStage) {
		try {
			Parent root = FXMLLoader.load(getClass().getResource("ExpandableTextAreaTest.fxml"));
			Scene scene = new Scene(root,400,400);
			primaryStage.setScene(scene);
			primaryStage.show();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		launch(args);
	}
}

this code has memory leak because it uses AnimationTimer class with heavy action. During time this control will be consume huge amount of memory. Do not use it!

this code has memory leak because it uses AnimationTimer class with heavy action. During time this control will be consume huge amount of memory. Do not use it!

The AnimationTimer does essentially nothing until the lookup succeeds, and when the lookup succeeds, it stops. It won't consume any appreciable memory.

@james-d Our company used this code in production. And after profiling the app, we found out that this class consumed near 80% of all app memory when opening the application for a long time (for example for 10 hour running app).