How can I modify data from another controller class? - javafx-8

Question

I have a main class (Main.java), two FXML files (FXML1.fxml, FXML2.fxml) and the corresponding controller (FXML1Controller.java, FXML2Controller.java).
In the FXML1.fxml I have two text fields and two buttons.
In the associated controller (FXML1Controller.java) I have declared the text fields and the button as follows:
public TextField textField1;
public TextField textField2;
public Button buttonchange;
public Button buttonOpenWindow;
public void open ()
{
...
stage.show ();
}
public void change ()
{
textField2.setText (textField1.getText ());
}
I type text into textField1. When I click on the buttonChange, then the text should be set in textfield2. Works. It's simple.
When I click the buttonOpen, then a new window opens.
There, I have only one button, but want to do the same.
So something in the way like this:
public void changeFromHere ()
{
FXMLController1 c1 = new FXMLController1 ();
c1.change ();
}
I also know that similar questions have been asked here.
But somehow it does not work the way I want it.
I always get a NullPointerException. For sure. I know.
So I have done the following:
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
...
public class FXML2Controller implements Initializable
{
...
public Button buttonChangeFromHere;
URL location;
FXMLLoader fxmlLoader;
Pane root;
FXMLController1 fc1;
public voidChangeFromHere ()
{
fc1.change ();
}
#Override
public void initialize (URL url, ResourceBundle rb)
{
try
{
location = getClass ().getResource ("FXML1.fxml");
fxmlLoader = new FXMLLoader (location);
root = (Pane) fxmlLoader.load ();
fc1 = (FXMLController1) fxmlLoader.getController ();
} catch (IOException ex)
{
Logger.getLogger (FXML2Controller.class.getName ()) .log (Level.SEVERE, null, ex);
}
}
...
}
Now I can not get a NullPointerException and it should work this way. But nothing happened !?
If I use for testing System.out.println (fc1.textField2.getText ());, then I get the text "Hello", which I have defined in JavaFXSceneBuilder.
If I remove the text in SceneBuilder, then I get "null". Sure. Likewise, I get "null" when I type in the term "Hello" (in textField1) while program is running.
I have also tried to initialize the textfields first in the initialize method. Then I also get always the text "Hello", although I typed "Byebye".
The solutions to similar questions in this forum can not help me.
That's why I put so a similar question again.
This code is also just an example. I can not paste my whole code here. What I really want to do is:
In my program I have a list (listView).
In the list are paths to files that I save as a file. Works fine (In the Main Controller, Main.fxml). There, I have a method public void save (). Now I want to call from another controller class's the save () method. But almost all variables are "null".
But they can't be "null", because the listView shows me the entrys.
I do not think that getter and setter methods are appropriate, because it would be very much redundant code. And I don't want that.
If someone could answer the question how to do it with textfields from example, then I would be grateful.
If it does not work with textfields, it will not work with other components, too:-(.
Thanks in advance.