Refactored scene switching with guava eventbus.

javafx-demo1/build.gradle

@@ -30,6 +30,7 @@ dependencies {
     implementation "org.openjfx:javafx-controls:15.0.1:${platform}"
     implementation "org.openjfx:javafx-graphics:15.0.1:${platform}"
     implementation "org.openjfx:javafx-fxml:15.0.1:${platform}"
+    implementation "com.google.guava:guava:30.1-jre"
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.6.0'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'
 }

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/JavaFxApplication.java

@@ -1,19 +1,20 @@
 package ch.tpolgrabia.javashowcase.javafxdemo;
 
-import ch.tpolgrabia.javashowcase.javafxdemo.controllers.LoginController;
+import ch.tpolgrabia.javashowcase.javafxdemo.models.SwitchToHomeEvent;
+import ch.tpolgrabia.javashowcase.javafxdemo.models.SwitchToLoginEvent;
+import ch.tpolgrabia.javashowcase.javafxdemo.services.SceneFactory;
+import ch.tpolgrabia.javashowcase.javafxdemo.services.SceneFactoryImpl;
+import com.google.common.eventbus.EventBus;
+import com.google.common.eventbus.Subscribe;
 import javafx.application.Application;
-import javafx.fxml.FXMLLoader;
-import javafx.scene.Parent;
-import javafx.scene.Scene;
 import javafx.stage.Stage;
 
-import java.io.IOException;
-import java.io.InputStream;
-
 // TODO add event bus like system to switch between views and add messaging
+// TODO add guice to provide better factory style di-injection.
 public class JavaFxApplication extends Application {
     private Stage stage;
-    private FXMLLoader loader;
+    private EventBus eventBus;
+    private SceneFactory factory;
 
     public static void main(String[] args) {
         launch(args);
@@ -22,43 +23,28 @@ public class JavaFxApplication extends Application {
     @Override
     public void start(Stage stage) {
         this.stage = stage;
-        this.loader = new FXMLLoader();
+        this.eventBus = new EventBus();
-
+        this.eventBus.register(this);
-        switchToLogin();
+        this.factory = new SceneFactoryImpl(eventBus);
+        eventBus.post(new SwitchToLoginEvent());
     }
 
     @Override
     public void stop() {
         this.stage = null;
-        this.loader = null;
     }
 
-    private void switchToLogin() {
+    @Subscribe
-        try (InputStream is = getClass().getClassLoader().getResourceAsStream("login.fxml")) {
+    public void switchToLogin(SwitchToLoginEvent event) {
-            var loader = new FXMLLoader();
+        stage.setScene(factory.loadLoginScene());
-            Parent root = loader.load(is);
+        stage.show();
-            LoginController loginController = loader.getController();
-            loginController.setSwitchToHome(this::switchToHome);
-            var scene = new Scene(root, 640, 480);
-            stage.setScene(scene);
-            stage.show();
 
-        } catch (IOException e) {
-            e.printStackTrace();
-            System.exit(1);
-        }
     }
 
-    public void switchToHome() {
+    @Subscribe
-        try (InputStream is = getClass().getClassLoader().getResourceAsStream("home.fxml")) {
+    public void switchToHome(SwitchToHomeEvent event) {
-            Parent root = loader.load(is);
+        stage.setScene(factory.loadHomeScene());
-            var scene = new Scene(root, 640, 480);
+        stage.show();
-            stage.setScene(scene);
-            stage.show();
 
-        } catch (IOException e) {
-            e.printStackTrace();
-            System.exit(1);
-        }
     }
 }

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/controllers/LoginController.java

@@ -1,5 +1,7 @@
 package ch.tpolgrabia.javashowcase.javafxdemo.controllers;
 
+import ch.tpolgrabia.javashowcase.javafxdemo.models.SwitchToHomeEvent;
+import com.google.common.eventbus.EventBus;
 import javafx.fxml.FXML;
 import javafx.scene.control.PasswordField;
 import javafx.scene.control.TextField;
@@ -10,16 +12,16 @@ public class LoginController {
     @FXML
     private PasswordField password;
 
-    private Runnable switchToHome;
+    private EventBus eventBus;
-
-    public void setSwitchToHome(Runnable switchToHome) {
-        this.switchToHome = switchToHome;
-    }
 
     @FXML
     public void handleLogin() {
         System.out.printf("Got data login: %s, password: %s\n",
                 login.getText(), password.getText());
-        switchToHome.run();
+        eventBus.post(new SwitchToHomeEvent());
+    }
+
+    public void setEventBus(EventBus eventBus) {
+        this.eventBus = eventBus;
     }
 }

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/models/SwitchToHomeEvent.java

@@ -0,0 +1,4 @@
+package ch.tpolgrabia.javashowcase.javafxdemo.models;
+
+public class SwitchToHomeEvent {
+}

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/models/SwitchToLoginEvent.java

@@ -0,0 +1,4 @@
+package ch.tpolgrabia.javashowcase.javafxdemo.models;
+
+public class SwitchToLoginEvent {
+}

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/services/SceneFactory.java

@@ -0,0 +1,9 @@
+package ch.tpolgrabia.javashowcase.javafxdemo.services;
+
+import javafx.scene.Scene;
+
+public interface SceneFactory {
+    Scene loadHomeScene();
+
+    Scene loadLoginScene();
+}

javafx-demo1/src/main/java/ch/tpolgrabia/javashowcase/javafxdemo/services/SceneFactoryImpl.java

@@ -0,0 +1,62 @@
+package ch.tpolgrabia.javashowcase.javafxdemo.services;
+
+import ch.tpolgrabia.javashowcase.javafxdemo.controllers.LoginController;
+import com.google.common.eventbus.EventBus;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public class SceneFactoryImpl implements SceneFactory {
+
+    private Scene homeScene;
+    private EventBus eventBus;
+
+    public SceneFactoryImpl(EventBus eventBus) {
+        this.eventBus = eventBus;
+    }
+
+    @Override
+    public Scene loadHomeScene() {
+        if (homeScene != null) {
+            return homeScene;
+        }
+
+        try (InputStream is = getClass().getClassLoader().getResourceAsStream("home.fxml")) {
+            Parent root = new FXMLLoader().load(is);
+
+            if (root == null) {
+                System.out.println("Couldn't find parent...");
+                return null;
+            }
+
+            homeScene = new Scene(root, 640, 480);
+            return homeScene;
+        } catch (IOException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    @Override
+    public Scene loadLoginScene() {
+        FXMLLoader loader = new FXMLLoader();
+        try (InputStream is = getClass().getClassLoader().getResourceAsStream("login.fxml")) {
+            Parent parent = loader.load(is);
+
+            if (parent == null) {
+                System.out.println("Couldn't load login component...");
+                return null;
+            }
+            LoginController loginController = loader.getController();
+            loginController.setEventBus(eventBus);
+            Scene scene = new Scene(parent, 640, 480);
+            return scene;
+        } catch (IOException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+}

javafx-demo1/src/main/java/module-info.java

@@ -3,6 +3,7 @@ module ch.tpolgrabia.javashowcase.javafx1demo {
     requires javafx.controls;
     requires javafx.graphics;
     requires javafx.fxml;
+    requires com.google.common;
 
     opens ch.tpolgrabia.javashowcase.javafxdemo to javafx.fxml;
     opens ch.tpolgrabia.javashowcase.javafxdemo.controllers to javafx.fxml;