JavaFX: 2 independent windows at once

Question

I\'d like to create 2 independent windows at once. One window would be able to hold an observable list, the other one would show the selected listobject\'s properties. I\'m tryi

Answer 1

The following is a demonstration of two windows (stages) sharing the same model.
The demonstration is kept as simple as possible: one window displays a list. The second window dynamically displays the items that where selected on the first:

The shared model holds the information that the two windows need. Basically a list of items, and a list of selected items:

package two_windows;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;

public class Model {

    private final ObservableList list;
    private ObservableList selected;

    Model(){
        list = FXCollections.observableArrayList();
    }

    void addMessage(String msg){
        list.add(msg);
    }

    ObservableList getMessages(){
        return list;
    }

    ObservableList getSelectedMessages(){
        return selected;
    }

    void setSelected(ObservableList selected) {
        this.selected = selected;
    }
}

The content of the first window is defined by List.fxml and its controller:

The controller accepts a Model, sets the selected items list in the model, listens and responds to model changes:

package two_windows;

import java.util.List;
import javafx.collections.ListChangeListener;
import javafx.fxml.FXML;
import javafx.scene.control.ListView;
import javafx.scene.control.SelectionMode;

public class ListController {

    @FXML ListView list;

    void setModel(Model model) {

        list.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);//allow multiple selection

        //sets the selected items of the list to the model 
        model.setSelected(list.getSelectionModel().getSelectedItems());

        //listen to changes in model, and respond
        model.getMessages().addListener(
                                        (ListChangeListener) c -> {
                                            c.next();
                                            addElements(c.getAddedSubList());
                                        }
                                    );
    }

    private void addElements(List msgList){

        for(String msg : msgList){
            list.getItems().add(msg);
        }
    }
}

The content of the second window is very similar to the first, and is defined by Selected.fxml:

And its controller, which like the other controller accepts a Model and responds to changes in it:

package two_windows;

import java.util.List;
import javafx.collections.ListChangeListener;
import javafx.fxml.FXML;
import javafx.scene.control.ListView;

public class SelectedController {

    @FXML ListView selected;

    void setModel(Model model) {

        //listen to changes in model, and respond
        model.getSelectedMessages().addListener(
                    (ListChangeListener) c -> {
                        c.next();
                        removeElements(c.getRemoved());
                        addElements(c.getAddedSubList());
                    }
                );
    }

    private void removeElements(List msgList){

        for(String msg : msgList){
            selected.getItems().remove(msg);
        }
    }

    private void addElements(List msgList){

        for(String msg : msgList){
            selected.getItems().add(msg);
        }
    }
}

Putting it all together and testing:

package two_windows;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class TwoWindows extends Application {

    private Model model;

    @Override
    public void start(Stage primaryStage) throws Exception{

        model = new Model();

        FXMLLoader listLoader = new FXMLLoader(getClass().getResource("List.fxml"));
        Parent list = listLoader.load();
        ListController listController = listLoader.getController();
        listController.setModel(model);

        FXMLLoader selectedLoader = new FXMLLoader(getClass().getResource("Selected.fxml"));
        Parent selected = selectedLoader.load();
        SelectedController selectedController = selectedLoader.getController();
        selectedController.setModel(model);

        primaryStage.setScene(new Scene(list));
        primaryStage.setX(350); primaryStage.setY(300);

        Stage secondaryStage = new Stage();
        secondaryStage.setScene(new Scene(selected));
        secondaryStage.setX(550); secondaryStage.setY(300);

        addMessages();
        primaryStage.show();
        secondaryStage.show();
    }

    private void addMessages() {

        int counter = 0;
        while(counter < 15) {
            model.addMessage("message number "+ counter++);
        }
    }

    public static void main(final String[] args) {
        launch(args);
    }
}