Switch Between Two Scenes: StackOverflow Question https://stackoverflow.com/questions/60358603/how-to-call-a-void-main-class-from-another-class-javafx

SceneOne.java

import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @author blj0011
 */
public class SceneOne
{
    private final Scene scene1;
    private final Stage primaryStage;
    private final Button button1 = new Button("Go to scene 2");
    private final Label label1 = new Label("This is the first scene");

    public SceneOne(Stage primaryStage)
    {
        VBox layout1 = new VBox(20);
        layout1.getChildren().addAll(label1, button1);
        scene1 = new Scene(layout1, 300, 250);

        this.primaryStage = primaryStage;
    }

    public Scene getScene1()
    {
        return scene1;
    }

    public void setSceneToSwitchTo(Scene scene)
    {
        button1.setOnAction(e -> this.primaryStage.setScene(scene));
    }
}

SceneTwo.java

import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @author blj0011
 */
public class SceneTwo
{
    private final Scene scene2;
    private final Stage primaryStage;
    Label label2 = new Label("This is the second scene");
    Button button2 = new Button("Go to scene 1");

    public SceneTwo(Stage primaryStage)
    {
        VBox layout2 = new VBox(20);
        layout2.getChildren().addAll(label2, button2);
        scene2 = new Scene(layout2, 300, 250);

        this.primaryStage = primaryStage;
    }

    public Scene getScene2()
    {
        return scene2;
    }

    public void setSceneToSwitchTo(Scene scene)
    {
        button2.setOnAction(e -> this.primaryStage.setScene(scene));
    }
}

TestingGroundsTwo.java

import javafx.application.Application;
import javafx.stage.Stage;

/**
 *
 * @author blj0011
 */
public class TestingGroundsTwo extends Application
{
    @Override
    public void start(Stage primaryStage)
    {
        SceneOne sceneOne = new SceneOne(primaryStage);
        SceneTwo sceneTwo = new SceneTwo(primaryStage);

        sceneOne.setSceneToSwitchTo(sceneTwo.getScene2());
        sceneTwo.setSceneToSwitchTo(sceneOne.getScene1());

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(sceneOne.getScene1());
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        launch(args);
    }

}