Loony Corn JavaFX course on Udemy -- experiments with properties on lecture 18

Lecture18a

package loonycorn.javafx;

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

public class Lecture18a extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        TextArea src1   = new TextArea();
        TextArea src2   = new TextArea();
        TextArea dst    = new TextArea();
        MyModel model = new MyModel();

        // NOT WORKING AS EXPECTED:
        // the second binding simply replace the first.
        // only update of "src2" will update the "dst" text
        model.simpleStringProperty().bind(src1.textProperty());
        model.simpleStringProperty().bind(src2.textProperty());
        dst.textProperty().bind(model.simpleStringProperty());
        
        VBox root = new VBox(src1,src2,dst);
        Scene scene = new Scene(root, 500, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

Lecture18b

package loonycorn.javafx;

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

public class Lecture18a extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        TextArea src1   = new TextArea();
        TextArea src2   = new TextArea();
        TextArea dst    = new TextArea();
        MyModel model = new MyModel();

        // WORKING AS EXPECTED:
        // update of any "src" text area will overwrite the "dst" text
        src1.textProperty().addListener(e -> model.setSimpleString(src1.getText()));
        src2.textProperty().addListener(e -> model.setSimpleString(src2.getText()));
        dst.textProperty().bind(model.simpleStringProperty());
        
        VBox root = new VBox(src1,src2,dst);
        Scene scene = new Scene(root, 500, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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

Lecture18c

package loonycorn.javafx;

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

public class Lecture18a extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        TextArea src1   = new TextArea();
        TextArea src2   = new TextArea();
        TextArea dst    = new TextArea();
        MyModel model = new MyModel();

        // KEEP ALL IN SYNC:
        // update of any "src" text area will overwrite the "dst" text and the other "src"
        src1.textProperty().addListener(e -> model.setSimpleString(src1.getText()));
        src1.textProperty().addListener((observable, oldValue, newValue) -> { 
            // prevent infinite recursion
            if (!oldValue.equals(newValue)) {
                src2.setText(newValue);
            }
        });
        src2.textProperty().addListener(e -> model.setSimpleString(src2.getText()));
        src2.textProperty().addListener((observable, oldValue, newValue) -> { 
            // prevent infinite recursion
            if (!oldValue.equals(newValue)) {
                src1.setText(newValue);
            }
        });
        dst.textProperty().bind(model.simpleStringProperty());
        
        VBox root = new VBox(src1,src2,dst);
        Scene scene = new Scene(root, 500, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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