TextArea setText won't show the new Text
<p>I got some Problems with a TextArea.
I tried to set a new Text after pressing a button.
But the GUI doesn't the new Text. If I check the textarea with get Text(), the console is showing the new Text. So there must be a problem maybe with the View class..</p>

<p>Hope you guys can help me.</p>

<p>Little Codeexplaining:
The Class Main FDSAPP is starting the App with StartView. From StartView I'm switching to NewPCapView and editing some stuff. So when I press Apply the text in protocollTextArea should change to "Pcap created and saved..."</p>

<p>Here is the Code:</p>

<pre><code>public class View{
    ...
   public TextArea mainTextArea = new TextArea("--Framework Data Streams--\n     
   --A Framework to create and to merge Pcaps :D--"),
   protocollTextArea = new TextArea("Just showing what you did");
    ...
 }



public class NewPCapView extends View{
    ...
    public void init(){     
        ...
        //alle Listener
        apply.setOnAction(new EventHandler&lt;ActionEvent&gt;() {
               @Override
               public void handle(ActionEvent event) {
                   applypressed = true;
                   try {
                    String filename = "InhaltOwnPCap.xml";
                    that.getControl().makeXMLFromOwnPcap(filename);

                    that.getControl().getContentFromXMLForOwnPcap(filename);

                    that.closeSecondStage();

                    protocollTextArea.setText("Pcap created and saved  
                    under C://Temp/outputfile.pcap");

                    that.primaryStage.toFront();

                    System.out.println(protocollTextArea.getText());

                   }catch (XMLStreamException | FileNotFoundException e) {
                       e.printStackTrace();
                   }
               }
           });

        ...
}


public class StartView extends View{
    ...

    /**
     * Listener
     */
    public void initListener(){
        ...
        createOwnPCap.setOnAction(new EventHandler&lt;ActionEvent&gt;() {
            @Override
            public void handle(ActionEvent event) {
                that.makePCapViewUI();
            }
        });     
    }

    public void initCenter(){
        hBox1 = new HBox();
        mainTextArea.setMinWidth(600);
        mainTextArea.setEditable(true);
        textAreaCSS(mainTextArea);
        hBox1.getChildren().add(mainTextArea);
    }

    ....

    public void initRight(){
        vBox = new VBox();
        protocollTextArea.setEditable(false);
        protocollTextArea.setWrapText(true);
        Label protokoll = new Label("Protocoll: ");
        Button save = new Button("Save");

        //Bereich Protokoll
        protokollCSS(protokoll);

        //Bereich TextArea
        textAreaCSS(protocollTextArea);

        //Speichern fehlt noch

        vBox.getChildren().addAll(protokoll,protocollTextArea,save);
    }


    /**
     * Helpingmethods
     */
    public void protokollCSS(Label protokoll){
        protokoll.setStyle("-fx-border-color: grey; "
                +"-fx-border-width: 1;"
                +"-fx-background-color: white");
    }

    public void textAreaCSS(TextArea textArea){
        textArea.setPrefRowCount(20); textArea.setPrefColumnCount(25);
        textArea.setStyle("-fx-border-color: grey;"
                         +"-fx-border-width: 1");
    }
    ...
}


    public class FDSApp extends Application {
      private FDSApp that = this;
      public Stage secondStage;
      public Stage primaryStage;
      public BorderPane root;
      private StartView startView;
      private NewPCapView pCapView;
      private Controller controller;
      private Scene mainScene = null;

      @Override
      public void start(Stage stage) throws Exception {
        this.primaryStage = stage;
        root = new BorderPane();
        startView = new StartView(that);
        pCapView = new NewPCapView(that);
        controller = new Controller(that,pCapView);
        initUI(primaryStage);
    }

    public void initUI(Stage primaryStage){
        //Fenster konfigurieren und anzeigen
        primaryStage.setTitle("...");
        primaryStage.setResizable(false);

        //Hintergrund
        root.setStyle("-fx-background-color: lightsteelblue");
        root.setTop(startView.getHBox());
        root.setCenter(startView.getHBox1());
        root.setLeft(startView.getHBox2());
        root.setRight(startView.getVBox());

        Scene mainScene = new  
                     Scene(root,startView.getWidth(),startView.getHeight());
        primaryStage.setScene(mainScene);
        primaryStage.show();
    }

    public void makePCapViewUI(){
        primaryStage.toBack(); //Macht die Primary invisible
        secondStage = new Stage();
        secondStage.setTitle("Creating PCap");
        secondStage.setScene(pCapView.getPCapScene());
        secondStage.show();
    }

    ....
}
</code></pre>