JavaのFXMLコントローラを使用して他のメソッドを呼び出しますか？

Question

JavaFXシーンビルダを使用してUIルックを作成しました。コントローラを使用することができ、ボタンをクリックするとコンソールに印刷されます。

私の問題は、Javaプログラムから他の関数​​を呼び出す方法です。 コントローラに新しいオブジェクトを作成して他のメソッドを呼び出すと、エラーが発生します。ここで

は私がと対話するクラスです：

public class GOcommand extends Command { 

    public GOcommand(String firstWord, String secondWord, String thirdWord) { 
     super(firstWord, secondWord, thirdWord); 
    } 

    public GOcommand() {} 

    @Override 
    public boolean execute(Player player) { 
     if (!hasSecondWord()) { 
      // if there is no second word, we don't know where to go... 
      Game.out.println(Game.messages.getString("goWhere")); 
      return false; 
     } 

     String direction = getSecondWord(); 
     player.goRoom(direction); 
     return false; 
    } 
    } 

Here is the controller class: 

    public class FXMLDocumentController implements Initializable { 

    Player player; 

    @FXML 
    private TextArea textArea; 

    @FXML 
    private Button northBtn; 

    @FXML 
    private Button giveBtn; 

    @FXML 
    private Button CloseBtn; 

    @FXML 
    private Button eastBtn; 

    @FXML 
    private Button dropBtn; 

    @FXML 
    private Button southBtn; 

    @FXML 
    private Button WestBtn; 

    @FXML 
    private Button helpBtn; 

    @FXML 
    private Button takeBtn; 

    @FXML 
    private void exitGame() { 
     System.exit(1); 
    } 

    @FXML 
    void northClicked(ActionEvent event) { 
     textArea.appendText("Go North button Clicked\n"); 
     player.goRoom("NORTH"); 
    } 

    @FXML 
    private void eastClicked(ActionEvent event) { 
     textArea.appendText("Go East button Clicked\n"); 
    } 

    @FXML 
    private void southClicked(ActionEvent event) { 
     textArea.appendText("Go South button Clicked\n"); 
    } 

    @FXML 
    private void westClicked(ActionEvent event) { 
     textArea.appendText("Go West button Clicked\n"); 
    } 

    @FXML 
    private void dropClicked(ActionEvent event) { 

    } 

    @FXML 
    private void takeClicked(ActionEvent event) { 
     textArea.appendText("Take button Clicked\n"); 
    } 

    @FXML 
    private void giveClicked(ActionEvent event) { 
     textArea.appendText("Give button Clicked\n"); 
    } 

    @FXML 
    private void helpClicked(ActionEvent event) { 
     textArea.appendText("Help me know!\n"); 
    } 


    @Override 
    public void initialize(URL url, ResourceBundle rb) { 
     // TODO 
    } 
    } 

そして、私はプレイヤー作成したので、これらのエラーです：あなたはそれを示し投稿スタックトレースの下部にある

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException 
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774) 
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657) 
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) 
    at javafx.event.Event.fireEvent(Event.java:198) 
    at javafx.scene.Node.fireEvent(Node.java:8411) 
    at javafx.scene.control.Button.fire(Button.java:185) 
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182) 
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96) 
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89) 
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218) 
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) 
    at javafx.event.Event.fireEvent(Event.java:198) 
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3757) 
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485) 
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) 
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:380) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416) 
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389) 
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415) 
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555) 
    at com.sun.glass.ui.View.notifyMouse(View.java:937) 
Caused by: java.lang.reflect.InvocationTargetException 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71) 
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275) 
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769) 
    ... 45 more 
Caused by: java.lang.NullPointerException 
    at assignment2.FXMLDocumentController.northClicked(FXMLDocumentController.java:62) 
    ... 55 more 

Answer 1

をNPE、あなたがアクセスしているフィールド 'player'。そして私が見ることから、その分野は初期化されていません。さもなければ、このコードは完全にうまくいくでしょう。多くの場合、nullのフィールドにアクセスすることによって引き起こされJavaFXアプリケーションに

Player player = new Player(); 

アンにInvocationTargetException：

Answer 2

はあなたのようなプレーヤーの新しいインスタンスを作成する必要があります。 JavaFXアプリケーションを作成するときは、そのことを覚えておいてください！