Q:

How to add JFXPanel to already existing swing app

I am very stuck in knowing what to do to integrate my JFXPanel (which is an mp3 player) into an existing Swing app that - which is a JFrame with several different JPanels added to it. I am a complete noob to JavaFX and it is very different from swing. 
I am able to get the code that is below to run and do what I want. It will play mp3 files from a directory that I have them contained in. This is code from a sample that someone wrote. My issue is that this code creates the the JFrame, has the main method and everything just in this code. I have a swing application that is already made that I just want to add a single JFXPanel to that has the functionality as below. There are many new methods in JavaFX that I am very confused with and don't know how to use or where to put in my Swing app. Such as invokeLater runLater and initAndShowGUI. I know this is probably an annoying question and hard to answer from such a noob. I have a project that is due tomorrow night at midnight and I really want to get this implemented as part of the app. We haven't learned JavaFX in class and I didn't know it was going to me this tricky for me. 
package application;  

import java.io.*;  
import java.util.*;  

import javafx.application.Platform;  
import javafx.beans.value.*;  
import javafx.embed.swing.JFXPanel;  
import javafx.event.*;  
import javafx.geometry.Pos;  
import javafx.scene.Scene;  
import javafx.scene.control.*;  
import javafx.scene.layout.*;  
import javafx.scene.media.*;  
import javafx.util.Duration;  

import javax.swing.*;  

/** Example of playing all mp3 audio files in a given directory  
 * using a JavaFX MediaView launched from Swing  
 */  
public class JavaFXVideoPlayerLaunchedFromSwing {  
  private static void initAndShowGUI() {  
    // This method is invoked on Swing thread  
    JFrame frame = new JFrame("FX");  
    final JFXPanel fxPanel = new JFXPanel();  
    frame.add(fxPanel);  
    frame.setBounds(200, 100, 800, 250);  
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);  
    frame.setVisible(true);  

    Platform.runLater(new Runnable() {  
      @Override public void run() {  
        initFX(fxPanel);          
      }  
    });  
  }  

  private static void initFX(JFXPanel fxPanel) {  
    // This method is invoked on JavaFX thread  
    Scene scene = new SceneGenerator().createScene();  
    fxPanel.setScene(scene);  
  }  

  public static void main(String[] args) {  
    SwingUtilities.invokeLater(new Runnable() {  
      @Override public void run() {  
        initAndShowGUI();  
      }  
    });  
  }  
}  

class SceneGenerator {      
  final Label currentlyPlaying = new Label();  
  final ProgressBar progress = new ProgressBar();  
  private ChangeListener<Duration> progressChangeListener;  

  public Scene createScene() {  
    final StackPane layout = new StackPane();  

    // determine the source directory for the playlist  
    final File dir = new File("C:/Users/Mark/Copy/Mp3Directory");  
    if (!dir.exists() || !dir.isDirectory()) {  
      System.out.println("Cannot find video source directory: " + dir);  
      Platform.exit();  
      return null;  
    }  

    // create some media players.  
    final List<MediaPlayer> players = new ArrayList<MediaPlayer>();  
    for (String file : dir.list(new FilenameFilter() {  
      @Override public boolean accept(File dir, String name) {  
        return name.endsWith(".mp3");  
      }  
    })) players.add(createPlayer("file:///" + (dir + "\\" + file).replace("\\", "/").replaceAll(" ", "%20")));  
    if (players.isEmpty()) {  
      System.out.println("No audio found in " + dir);  
      Platform.exit();  
      return null;  
    }      

    // create a view to show the mediaplayers.  
    final MediaView mediaView = new MediaView(players.get(0));  
    final Button skip = new Button("Skip");  
    final Button play = new Button("Pause");  

    // play each audio file in turn.  
    for (int i = 0; i < players.size(); i++) {  
      final MediaPlayer player     = players.get(i);  
      final MediaPlayer nextPlayer = players.get((i + 1) % players.size());  
      player.setOnEndOfMedia(new Runnable() {  
        @Override public void run() {  
          player.currentTimeProperty().removeListener(progressChangeListener);  
          mediaView.setMediaPlayer(nextPlayer);  
          nextPlayer.play();  
        }  
      });  
    }  

    // allow the user to skip a track.  
    skip.setOnAction(new EventHandler<ActionEvent>() {  
      @Override public void handle(ActionEvent actionEvent) {  
        final MediaPlayer curPlayer = mediaView.getMediaPlayer();  
        MediaPlayer nextPlayer = players.get((players.indexOf(curPlayer) + 1) % players.size());  
        mediaView.setMediaPlayer(nextPlayer);  
        curPlayer.currentTimeProperty().removeListener(progressChangeListener);  
        curPlayer.stop();  
        nextPlayer.play();  
      }  
    });  

    // allow the user to play or pause a track.  
    play.setOnAction(new EventHandler<ActionEvent>() {  
      @Override public void handle(ActionEvent actionEvent) {  
        if ("Pause".equals(play.getText())) {  
          mediaView.getMediaPlayer().pause();  
          play.setText("Play");  
        } else {  
          mediaView.getMediaPlayer().play();  
          play.setText("Pause");  
        }  
      }  
    });  

    // display the name of the currently playing track.  
    mediaView.mediaPlayerProperty().addListener(new ChangeListener<MediaPlayer>() {  
      @Override public void changed(ObservableValue<? extends MediaPlayer> observableValue, MediaPlayer oldPlayer, MediaPlayer newPlayer) {  
        setCurrentlyPlaying(newPlayer);  
      }  
    });  

    // start playing the first track.  
    mediaView.setMediaPlayer(players.get(0));  
    mediaView.getMediaPlayer().play();  
    setCurrentlyPlaying(mediaView.getMediaPlayer());  

    // silly invisible button used as a template to get the actual preferred size of the Pause button.  
    Button invisiblePause = new Button("Pause");  
    invisiblePause.setVisible(false);  
    play.prefHeightProperty().bind(invisiblePause.heightProperty());  
    play.prefWidthProperty().bind(invisiblePause.widthProperty());  

    // layout the scene.  
    layout.setStyle("-fx-background-color: cornsilk; -fx-font-size: 20; -fx-padding: 20; -fx-alignment: center;");  
    layout.getChildren().addAll(  
      invisiblePause,  
      VBoxBuilder.create().spacing(10).alignment(Pos.CENTER).children(  
        currentlyPlaying,  
        mediaView,  
        HBoxBuilder.create().spacing(10).alignment(Pos.CENTER).children(skip, play, progress).build()  
      ).build()  
    );  
    progress.setMaxWidth(Double.MAX_VALUE);  
    HBox.setHgrow(progress, Priority.ALWAYS);  
    return new Scene(layout, 800, 600);  
  }  

  /** sets the currently playing label to the label of the new media player and updates the progress monitor. */  
  private void setCurrentlyPlaying(final MediaPlayer newPlayer) {  
    progress.setProgress(0);  
    progressChangeListener = new ChangeListener<Duration>() {  
      @Override public void changed(ObservableValue<? extends Duration> observableValue, Duration oldValue, Duration newValue) {  
        progress.setProgress(1.0 * newPlayer.getCurrentTime().toMillis() / newPlayer.getTotalDuration().toMillis());  
      }  
    };  
    newPlayer.currentTimeProperty().addListener(progressChangeListener);  

    String source = newPlayer.getMedia().getSource();  
    source = source.substring(0, source.length() - ".mp4".length());  
    source = source.substring(source.lastIndexOf("/") + 1).replaceAll("%20", " ");  
    currentlyPlaying.setText("Now Playing: " + source);  
  }  

  /** @return a MediaPlayer for the given source which will report any errors it encounters */  
  private MediaPlayer createPlayer(String aMediaSrc) {  
    System.out.println("Creating player for: " + aMediaSrc);  
    final MediaPlayer player = new MediaPlayer(new Media(aMediaSrc));  
    player.setOnError(new Runnable() {  
      @Override public void run() {  
        System.out.println("Media error occurred: " + player.getError());  
      }  
    });  
    return player;  
  }  
}  

A:

JFXPanel extends javax.swing.JComponent so you will add the JFXPanel to the JFrame just as you would with other Swing components:    jFrame.getContentPane().add(myJFXPanel) 
SSCCE: 
package stack;

import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.effect.Reflection;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class FXInSwing extends JFrame{

    JFXPanel panel;
    Scene scene;
    StackPane stack;
    Text hello;

    boolean wait = true;

    public FXInSwing(){
        panel = new JFXPanel();
        Platform.runLater(new Runnable(){
            @Override
            public void run() {
                stack = new StackPane();
                scene = new Scene(stack,300,300);
                hello = new Text("Hello");

                scene.setFill(Color.BLACK);
                hello.setFill(Color.WHEAT);
                hello.setEffect(new Reflection());

                panel.setScene(scene);
                stack.getChildren().add(hello);

                wait = false;
            }
        });
        this.getContentPane().add(panel);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(300, 300);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run() {
                new FXInSwing();
            }
        });
    }
}  

Remember when you are working with a JFXPanel, you should initialize it on the Swing Event Dispatching Thread but the setScene() should be done on the JavaFX Application Thread. Else, you will get an exception.

