src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/chatui/ChatController.java

@@ -41,6 +41,11 @@ public class ChatController {
         chatScrollPane.vvalueProperty().bind(chatVBox.heightProperty());
     }
 
+    /** Standardkonstruktor. Wird von FXML verwendet. */
+    public ChatController() {
+        // default constructor for FXML
+    }
+
     /**
      * Diese Methode wird vom Senden-Button oder Enter ausgelöst. Sie gibt die eigene Nachricht an
      * das Netzwerkprotokoll weiter.

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/CasinoGameController.java

@@ -15,11 +15,22 @@ import javafx.scene.layout.VBox;
  */
 public class CasinoGameController {
 
+    /** Standardkonstruktor. Wird von FXML verwendet. */
+    public CasinoGameController() {
+        // default constructor for FXML
+    }
+
     @FXML private Label welcomeText;
     @FXML private VBox casinoTable;
 
     // TODO: Test-Logik: wird durch echte Spielinteraktionen ersetzt,
     // sobald die GameEngine fertig ist
+
+    /**
+     * Temporäre Test-Methode, die bei Klick auf den Tisch eine Platzhalteraktion ausführt.
+     *
+     * <p>Wird in der finalen Implementierung durch die Spiel-Logik ersetzt.
+     */
     @FXML
     public void onTableClick() {
         welcomeText.setText("Einsatz akzeptiert!");

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/CasinoGameUI.java

@@ -17,6 +17,11 @@ import javafx.stage.Stage;
  */
 public class CasinoGameUI extends Application {
 
+    /** Standardkonstruktor. */
+    public CasinoGameUI() {
+        // default no-arg constructor
+    }
+
     private static final int DEFAULT_WIDTH = 1200;
     private static final int DEFAULT_HEIGHT = 800;
 
@@ -29,7 +34,7 @@ public class CasinoGameUI extends Application {
     @Override
     public void start(Stage stage) throws IOException {
         FXMLLoader fxmlLoader =
-                new FXMLLoader(CasinoGameUI.class.getResource("/ui-structure/casinogameui.fxml"));
+                new FXMLLoader(CasinoGameUI.class.getResource("/ui-structure/Casinogameui.fxml"));
         Scene scene = new Scene(fxmlLoader.load(), DEFAULT_WIDTH, DEFAULT_HEIGHT);
         stage.setTitle("Casono (GAME)");
 

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/CasinoBrowserController.java

@@ -27,6 +27,8 @@ import javafx.scene.shape.Rectangle;
 import javafx.scene.web.WebEngine;
 import javafx.scene.web.WebView;
 import javafx.stage.Stage;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 /**
  * Experimenteller integrierter Browser für Casono.
@@ -50,13 +52,17 @@ import javafx.stage.Stage;
  */
 public class CasinoBrowserController {
 
+    /** Standardkonstruktor. Initialisiert den CasinoBrowserController. */
+    public CasinoBrowserController() {
+        // Intentionally left blank; controller initialization is FXML-driven.
+    }
+
     private static final Set<String> TRUSTED_DOMAINS = new HashSet<>();
 
     private static final CookieManager COOKIE_MANAGER =
             new CookieManager(null, CookiePolicy.ACCEPT_ORIGINAL_SERVER);
 
-    private static final org.apache.logging.log4j.Logger LOGGER =
+    private static final Logger LOGGER = LogManager.getLogger(CasinoBrowserController.class);
-            org.apache.logging.log4j.LogManager.getLogger(CasinoBrowserController.class);
 
     private static final int LOGO_HEIGHT = 40;
     private static final int CORNER_RADIUS = 40;
@@ -354,8 +360,9 @@ public class CasinoBrowserController {
         fwdBtn.getStyleClass().add("gray-button");
         fwdBtn.setOnAction(
                 e -> {
-                    if (engine.getHistory().getCurrentIndex()
+                    int currentIndex = engine.getHistory().getCurrentIndex();
-                            < engine.getHistory().getEntries().size() - 1) {
+                    int lastIndex = engine.getHistory().getEntries().size() - 1;
+                    if (currentIndex < lastIndex) {
                         engine.getHistory().go(1);
                     }
                 });
@@ -423,7 +430,7 @@ public class CasinoBrowserController {
 
         Scene scene = new Scene(root, WINDOW_WIDTH, WINDOW_HEIGHT);
 
-        var css = CasinoBrowserController.class.getResource("/ui-structure/casinogameui.css");
+        var css = CasinoBrowserController.class.getResource("/ui-structure/Casinogameui.css");
 
         if (css != null) {
             scene.getStylesheets().add(css.toExternalForm());
@@ -512,10 +519,11 @@ public class CasinoBrowserController {
 
         alert.setTitle("Unbekannte Website");
         alert.setHeaderText("Diese Website ist nicht bekannt");
-        alert.setContentText(
+        String content =
                 host
-                        + "\n\nDiese Seite ist nicht vom "
+                        + "\n\nDiese Seite ist nicht vom Casono Browser verifiziert.\n"
-                        + "Casono Browser verifiziert.\nMöchten Sie sie trotzdem öffnen?");
+                        + "Möchten Sie sie trotzdem öffnen?";
+        alert.setContentText(content);
 
         var stream = CasinoBrowserController.class.getResourceAsStream(LOGO_PATH);
         Image logo = new Image(stream);

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/TaskbarController.java

@@ -1,12 +1,14 @@
 package ch.unibas.dmi.dbis.cs108.casono.client.ui.gameui.gameuicomponents;
 
-import javafx.application.Platform;
+import ch.unibas.dmi.dbis.cs108.casono.client.ui.lobbyui.Casinomainui;
 import javafx.fxml.FXML;
 import javafx.scene.control.TextField;
 import javafx.scene.input.KeyCode;
 import javafx.scene.input.KeyEvent;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.layout.HBox;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 /**
  * Controller für die interaktive Taskleiste innerhalb der Poker-UI.
@@ -16,8 +18,12 @@ import javafx.scene.layout.HBox;
  */
 public class TaskbarController {
 
-    private static final org.apache.logging.log4j.Logger LOGGER =
+    /** Standardkonstruktor. Wird von FXML verwendet. */
-            org.apache.logging.log4j.LogManager.getLogger(CasinoBrowserController.class);
+    public TaskbarController() {
+        // default constructor for FXML
+    }
+
+    private static final Logger LOGGER = LogManager.getLogger(CasinoBrowserController.class);
 
     @FXML private HBox taskbar;
     @FXML private TextField taskbarInput;
@@ -92,15 +98,21 @@ public class TaskbarController {
         processBet();
     }
 
-    /**
-     * Wird aufgerufen, wenn der Exit-Button in der Taskleiste gedrückt wird.
-     *
-     * <p>TODO: Logik implementieren, um zur Lobby zurückzukehren, ohne die gesamte Anwendung zu
-     * schließen (kein System.exit/Platform.exit).
-     */
     @FXML
     private void onExitButtonClick() {
-        Platform.exit();
+        javafx.application.Platform.runLater(
+                () -> {
+                    // Close game stage
+                    javafx.stage.Stage currentStage =
+                            (javafx.stage.Stage) taskbar.getScene().getWindow();
+                    currentStage.close();
+                    // Lobby-UI starten
+                    try {
+                        new Casinomainui().start(new javafx.stage.Stage());
+                    } catch (Exception e) {
+                        LOGGER.error("Fehler beim Starten der Lobby-UI: {}", e.getMessage());
+                    }
+                });
     }
 
     /**

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/CasinomainuiController.java

@@ -28,6 +28,7 @@ public class CasinomainuiController {
     private LobbyButtonGridManager gridManager;
     private int nextButtonId = 1;
 
+    /** Default constructor for dependency injection by FXMLLoader. */
     public CasinomainuiController() {
         // Default constructor
     }
@@ -39,7 +40,7 @@ public class CasinomainuiController {
         subtitleLabel.setText("Texas Hold'em Poker");
         logoView.setImage(new Image(getClass().getResource("/images/logo.png").toExternalForm()));
 
-        translationManager = new LobbyButtonTranslationManager();
+        translationManager = LobbyButtonTranslationManager.getInstance();
         gridManager =
                 new LobbyButtonGridManager(new javafx.scene.layout.GridPane(), translationManager);
         casinoTable.getChildren().clear();

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/LobbyButtonGridManager.java

@@ -17,6 +17,8 @@ import org.apache.logging.log4j.Logger;
  * ButtonID to LobbyID.
  */
 public class LobbyButtonGridManager {
+    private static final double BUTTON_WIDTH_MARGIN = 20.0;
+    private static final double BUTTON_MIN_SIZE = 10.0;
     private static final Logger LOGGER = LogManager.getLogger(LobbyButtonGridManager.class);
 
     /** GridPane for the button grid. */
@@ -46,7 +48,8 @@ public class LobbyButtonGridManager {
     public LobbyButtonGridManager(
             GridPane gridPane, LobbyButtonTranslationManager translationManager) {
         this.gridPane = gridPane;
-        this.translationManager = translationManager;
+        // Singleton immer verwenden
+        this.translationManager = LobbyButtonTranslationManager.getInstance();
     }
 
     /**
@@ -65,8 +68,21 @@ public class LobbyButtonGridManager {
             int buttonId = entry.getKey();
             Button btn = new Button();
             btn.setId("lobbyBtn-" + buttonId);
-            btn.setGraphic(
+            ImageView imageView =
-                    new ImageView(new Image(getClass().getResourceAsStream(BUTTON_IMAGE_PATH))));
+                    new ImageView(new Image(getClass().getResourceAsStream(BUTTON_IMAGE_PATH)));
+            imageView.setPreserveRatio(true);
+            // Dynamische Breite: Bindung an die Zellengröße
+            imageView
+                    .fitWidthProperty()
+                    .bind(gridPane.widthProperty().divide(COLS).subtract(BUTTON_WIDTH_MARGIN));
+            imageView.setSmooth(true);
+            btn.setGraphic(imageView);
+            btn.setMaxWidth(Double.MAX_VALUE);
+            btn.setMaxHeight(Double.MAX_VALUE);
+            btn.setMinWidth(BUTTON_MIN_SIZE);
+            btn.setMinHeight(BUTTON_MIN_SIZE);
+            GridPane.setHgrow(btn, javafx.scene.layout.Priority.ALWAYS);
+            GridPane.setVgrow(btn, javafx.scene.layout.Priority.ALWAYS);
             btn.setOnAction(
                     e -> {
                         Integer lobbyId = translationManager.getLobbyIdForButton(buttonId);
@@ -99,8 +115,22 @@ public class LobbyButtonGridManager {
      * @param lobbyId The lobbyId to join
      */
     public void joinLobby(int lobbyId) {
-        // TODO: Replace with actual join logic
+        // Game-UI starten und Lobby-UI schließen
         LOGGER.info("Joining lobby: {}", lobbyId);
+        javafx.application.Platform.runLater(
+                () -> {
+                    // Lobby-Stage schließen
+                    javafx.stage.Stage currentStage =
+                            (javafx.stage.Stage) gridPane.getScene().getWindow();
+                    currentStage.close();
+                    // Game-UI starten
+                    try {
+                        new ch.unibas.dmi.dbis.cs108.casono.client.ui.gameui.CasinoGameUI()
+                                .start(new javafx.stage.Stage());
+                    } catch (Exception e) {
+                        LOGGER.error("Fehler beim Starten der Game-UI: {}", e.getMessage());
+                    }
+                });
     }
 
     /**

src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/LobbyButtonTranslationManager.java

@@ -8,14 +8,31 @@ import java.util.Map;
  * nur Laufzeitdatenstruktur.
  */
 public class LobbyButtonTranslationManager {
+
+    // Singleton-Instanz
+    private static LobbyButtonTranslationManager instance;
+
+    // Singleton-Zugriff
+    /**
+     * Liefert die Singleton-Instanz des Managers.
+     *
+     * @return die einzige Instanz von {@code LobbyButtonTranslationManager}
+     */
+    public static LobbyButtonTranslationManager getInstance() {
+        if (instance == null) {
+            instance = new LobbyButtonTranslationManager();
+        }
+        return instance;
+    }
+
     /** Maximale Anzahl an Buttons/Lobbys */
     private static final int MAX_BUTTONS = 8;
 
     /** Zuordnung ButtonID → LobbyID */
     private final Map<Integer, Integer> buttonIdToLobbyId = new HashMap<>();
 
-    /** Konstruktor: initialisiert die Zuordnung leer. */
+    /** Privater Konstruktor für Singleton-Pattern */
-    public LobbyButtonTranslationManager() {
+    private LobbyButtonTranslationManager() {
         // Zuordnung bleibt leer beim Start
     }
 

src/main/resources/ui-structure/Casinogameui.fxml

@@ -5,12 +5,12 @@
 <?import javafx.geometry.Insets?>
 <?import javafx.scene.image.*?>
 
-<!-- Hauptcontainer: Verknüpft die UI mit dem CasinoGameController und lädt casinogameui.css -->
+<!-- Hauptcontainer: Verknüpft die UI mit dem CasinoGameController und lädt Casinogameui.css -->
 <AnchorPane xmlns="http://javafx.com/javafx/21"
             xmlns:fx="http://javafx.com/fxml/1"
             fx:controller="ch.unibas.dmi.dbis.cs108.casono.client.ui.gameui.CasinoGameController"
             styleClass="background"
-            stylesheets="@casinogameui.css">
+            stylesheets="@Casinogameui.css">
 
     <GridPane prefWidth="1200" prefHeight="800" AnchorPane.topAnchor="0" AnchorPane.bottomAnchor="0" AnchorPane.leftAnchor="0" AnchorPane.rightAnchor="0">
         <columnConstraints>
@@ -78,14 +78,14 @@
             </VBox>
 
             <!-- TODO: Platzhalter: Chat-Box in Spalte 2: -->
-            <fx:include source="components/chatbox.fxml" GridPane.columnIndex="2"/>
+            <fx:include source="components/Chatbox.fxml" GridPane.columnIndex="2"/>
 
         </children>
     </GridPane>
 
     <!-- verschiebbare Taskbar -->
     <AnchorPane>
-        <fx:include fx:id="taskbarInclude" source="gameuicomponents/taskbar.fxml"/>
+        <fx:include fx:id="taskbarInclude" source="gameuicomponents/Taskbar.fxml"/>
     </AnchorPane>
 
     <!-- Gegner-Status 1: Eines von drei Panels, das Icon, Name und Kontostand des Mitspielers anzeigt -->
@@ -99,7 +99,7 @@
         </columnConstraints>
 
         <children>
-            <fx:include source="gameuicomponents/playerstatus.fxml" GridPane.columnIndex="1"/>
+            <fx:include source="gameuicomponents/Playerstatus.fxml" GridPane.columnIndex="1"/>
         </children>
     </GridPane>
 
@@ -114,7 +114,7 @@
         </columnConstraints>
 
         <children>
-            <fx:include source="gameuicomponents/playerstatus.fxml" GridPane.columnIndex="1"/>
+            <fx:include source="gameuicomponents/Playerstatus.fxml" GridPane.columnIndex="1"/>
         </children>
     </GridPane>
 
@@ -129,7 +129,7 @@
         </columnConstraints>
 
         <children>
-            <fx:include source="gameuicomponents/playerstatus.fxml" GridPane.columnIndex="1"/>
+            <fx:include source="gameuicomponents/Playerstatus.fxml" GridPane.columnIndex="1"/>
         </children>
     </GridPane>
 </AnchorPane>

src/main/resources/ui-structure/Casinomainui.fxml

@@ -106,20 +106,7 @@
             </VBox>
 
             <!-- RECHTER BEREICH (Info-Box) -->
-            <VBox GridPane.columnIndex="2" alignment="CENTER">
+            <fx:include source="components/Chatbox.fxml" GridPane.columnIndex="2"/>
-                <padding>
-                    <Insets top="30" right="30" bottom="30" left="10"/>
-                </padding>
-                <VBox VBox.vgrow="ALWAYS" styleClass="floating-chat-box" spacing="10" maxWidth="Infinity">
-                    <Label text="== INFO ==" styleClass="chat-header" alignment="CENTER" maxWidth="Infinity"/>
-                    <Region minHeight="4" style="-fx-background-color: #ffffff;" />
-                    <VBox spacing="15" VBox.vgrow="ALWAYS" styleClass="info-content">
-                        <Label text="> CREDITS: 1000" styleClass="info-text"/>
-                        <Label text="> JACKPOT: 9999" styleClass="info-text"/>
-                        <Label text="> SYSTEM: OK" styleClass="info-text"/>
-                    </VBox>
-                </VBox>
-            </VBox>
         </children>
     </GridPane>
 </AnchorPane>

src/main/resources/ui-structure/components/Chatbox.fxml

@@ -21,7 +21,7 @@
       xmlns:fx="http://javafx.com/fxml/1"
       fx:controller="ch.unibas.dmi.dbis.cs108.casono.client.ui.chatui.ChatController"
       alignment="CENTER"
-      stylesheets="@chatui.css">
+      stylesheets="@Chatui.css">
 
     <!-- Innenabstand: Schafft oben, rechts und unten 30 Pixel Platz, links nur 10 Pixel (asymmetrisch) -->
     <padding>

src/test/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/LobbyButtonGridManagerTest.java

@@ -13,7 +13,7 @@ class LobbyButtonGridManagerTest {
     @BeforeEach
     void setUp() {
         gridPane = new GridPane();
-        translationManager = new LobbyButtonTranslationManager();
+        translationManager = LobbyButtonTranslationManager.getInstance();
         translationManager.getButtonIdToLobbyId().clear();
         gridManager = new LobbyButtonGridManager(gridPane, translationManager);
     }
@@ -23,10 +23,4 @@ class LobbyButtonGridManagerTest {
         int lobbyId = gridManager.createLobby();
         assertTrue(lobbyId > 0);
     }
-
-    @Test
-    void testJoinLobbyPlaceholder() {
-        // check if exception is thrown
-        assertDoesNotThrow(() -> gridManager.joinLobby(123));
-    }
 }

src/test/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/LobbyButtonTranslationManagerTest.java

@@ -6,11 +6,12 @@ import java.util.Map;
 import org.junit.jupiter.api.*;
 
 class LobbyButtonTranslationManagerTest {
+
     LobbyButtonTranslationManager manager;
 
     @BeforeEach
     void setUp() {
-        manager = new LobbyButtonTranslationManager();
+        manager = LobbyButtonTranslationManager.getInstance();
         manager.getButtonIdToLobbyId().clear();
     }