Trying to use Java lambda expression in a MVC example , don't know if there is more I can do ?

The MVC example below comes from Head First Design Patterns book .

This MVC example focus on the observer pattern (between Model & Controller) and the strategy pattern(between View & Controller).

Today I want to try to improve the code by using lambda expression , I could only change the Actionperformed part in the view to lambda expression .

I don't know if there are more places I could use lambda expression in this example ?

The begining of the example

Model part :
Subject ：

public interface BeatModelInterface {
    void initialize();

    void on();

    void off();

    void setBPM(int bpm);

    int getBPM();

    void registerObserver(BeatObserver o);

    void removeObserver(BeatObserver o);

    void registerObserver(BPMObserver o);

    void removeObserver(BPMObserver o);
}

public interface BeatObserver {
    void updateBeat();
}
public interface BPMObserver {
    void updateBPM();
}

ConcreteSubject ：

import javax.sound.midi.*;

import java.util.*;

public class BeatModel implements BeatModelInterface, MetaEventListener {
    Sequencer sequencer;
    ArrayList<BeatObserver> beatObservers = new ArrayList<BeatObserver>();

    ArrayList<BPMObserver> bpmObservers = new ArrayList<BPMObserver>();
    int bpm = 90;
    Sequence sequence;
    Track track;

    public void initialize() {
        setUpMidi(); 
        buildTrackAndStart();
    }

    public void on() {
        System.out.println("Starting the sequencer");
        sequencer.start();
        setBPM(90);
    }

    public void off() {
        setBPM(0);
        sequencer.stop(); 
    }

    public void setBPM(int bpm) {
        this.bpm = bpm;   
        sequencer.setTempoInBPM(getBPM()); 
        notifyBPMObservers();  
    }

    public int getBPM() {
        return bpm;
    }

    void beatEvent() {
        notifyBeatObservers();
    }


    public void registerObserver(BeatObserver o) {
        beatObservers.add(o);
    }

    public void notifyBeatObservers() {
        for(int i = 0; i < beatObservers.size(); i++) {
            BeatObserver observer = (BeatObserver)beatObservers.get(i);
            observer.updateBeat();
        }
    }

    public void registerObserver(BPMObserver o) {
        bpmObservers.add(o);
    }

    public void notifyBPMObservers() {
        for(int i = 0; i < bpmObservers.size(); i++) {
            BPMObserver observer = (BPMObserver)bpmObservers.get(i);
            observer.updateBPM();
        }
    }


    public void removeObserver(BeatObserver o) {
        int i = beatObservers.indexOf(o);
        if (i >= 0) {
            beatObservers.remove(i);
        }
    }



    public void removeObserver(BPMObserver o) {
        int i = bpmObservers.indexOf(o);
        if (i >= 0) {
            bpmObservers.remove(i);
        }
    }


    public void meta(MetaMessage message) {
        if (message.getType() == 47) {
            beatEvent();
            sequencer.start();
            setBPM(getBPM());
        }
    }


    public void setUpMidi() {
        try {
            sequencer = MidiSystem.getSequencer();
            sequencer.open();
            sequencer.addMetaEventListener(this);
            sequence = new Sequence(Sequence.PPQ,4);
            track = sequence.createTrack();
            sequencer.setTempoInBPM(getBPM());
            sequencer.setLoopCount(Sequencer.LOOP_CONTINUOUSLY);
        } catch(Exception e) {
            e.printStackTrace();
        }
    } 

    public void buildTrackAndStart() {
        int[] trackList = {35, 0, 46, 0};

        sequence.deleteTrack(null);
        track = sequence.createTrack();

        makeTracks(trackList);
        track.add(makeEvent(192,9,1,0,4));      
        try {
            sequencer.setSequence(sequence);                    
        } catch(Exception e) {
            e.printStackTrace();
        }
    } 

    public void makeTracks(int[] list) {        

        for (int i = 0; i < list.length; i++) {
            int key = list[i];

            if (key != 0) {
                track.add(makeEvent(144,9,key, 100, i));
                track.add(makeEvent(128,9,key, 100, i+1));
            }
        }
    }

    public  MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) {
        MidiEvent event = null;
        try {
            ShortMessage a = new ShortMessage();
            a.setMessage(comd, chan, one, two);
            event = new MidiEvent(a, tick);

        } catch(Exception e) {
            e.printStackTrace(); 
        }
        return event;
    }
        }

View part :
ConcreteObserver :

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class DJView implements ActionListener,  BeatObserver, BPMObserver {
    BeatModelInterface model;
    ControllerInterface controller;
    JFrame viewFrame;
    JPanel viewPanel;
    BeatBar beatBar;
    JLabel bpmOutputLabel;
    JFrame controlFrame;
    JPanel controlPanel;
    JLabel bpmLabel;
    JTextField bpmTextField;
    JButton setBPMButton;
    JButton increaseBPMButton;
    JButton decreaseBPMButton;
    JMenuBar menuBar;
    JMenu menu;
    JMenuItem startMenuItem;
    JMenuItem stopMenuItem;

    public DJView(ControllerInterface controller, BeatModelInterface model) {   

        this.controller = controller;  

        this.model = model;
        model.registerObserver((BeatObserver)this);
        model.registerObserver((BPMObserver)this);
    }

    public void createView() {
        // Create all Swing components here
        viewPanel = new JPanel(new GridLayout(1, 2));
        viewFrame = new JFrame("View");
        viewFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        viewFrame.setSize(new Dimension(100, 80));
        bpmOutputLabel = new JLabel("offline", SwingConstants.CENTER);
        beatBar = new BeatBar();
        beatBar.setValue(0);
        JPanel bpmPanel = new JPanel(new GridLayout(2, 1));
        bpmPanel.add(beatBar);
        bpmPanel.add(bpmOutputLabel);
        viewPanel.add(bpmPanel);
        viewFrame.getContentPane().add(viewPanel, BorderLayout.CENTER);
        viewFrame.pack();
        viewFrame.setVisible(true);
    }


    public void createControls() {
        // Create all Swing components here
        JFrame.setDefaultLookAndFeelDecorated(true);
        controlFrame = new JFrame("Control");
        controlFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        controlFrame.setSize(new Dimension(100, 80));

        controlPanel = new JPanel(new GridLayout(1, 2));

        menuBar = new JMenuBar();
        menu = new JMenu("DJ Control");
        startMenuItem = new JMenuItem("Start");
        menu.add(startMenuItem);
        startMenuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                controller.start();
            }
        });
        stopMenuItem = new JMenuItem("Stop");
        menu.add(stopMenuItem); 
        stopMenuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                controller.stop();
            }
        });
        JMenuItem exit = new JMenuItem("Quit");
        exit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        });

        menu.add(exit);
        menuBar.add(menu);
        controlFrame.setJMenuBar(menuBar);

        bpmTextField = new JTextField(2);
        bpmLabel = new JLabel("Enter BPM:", SwingConstants.RIGHT);
        setBPMButton = new JButton("Set");
        setBPMButton.setSize(new Dimension(10,40));
        increaseBPMButton = new JButton(">>");
        decreaseBPMButton = new JButton("<<");
        setBPMButton.addActionListener(this);
        increaseBPMButton.addActionListener(this);
        decreaseBPMButton.addActionListener(this);

        JPanel buttonPanel = new JPanel(new GridLayout(1, 2));

        buttonPanel.add(decreaseBPMButton);
        buttonPanel.add(increaseBPMButton);

        JPanel enterPanel = new JPanel(new GridLayout(1, 2));
        enterPanel.add(bpmLabel);
        enterPanel.add(bpmTextField);
        JPanel insideControlPanel = new JPanel(new GridLayout(3, 1));
        insideControlPanel.add(enterPanel);
        insideControlPanel.add(setBPMButton);
        insideControlPanel.add(buttonPanel);
        controlPanel.add(insideControlPanel);

        bpmLabel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
        bpmOutputLabel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));

        controlFrame.getRootPane().setDefaultButton(setBPMButton);
        controlFrame.getContentPane().add(controlPanel, BorderLayout.CENTER);

        controlFrame.pack();
        controlFrame.setVisible(true);
        }

    public void enableStopMenuItem() {
        stopMenuItem.setEnabled(true);
    }

    public void disableStopMenuItem() {
        stopMenuItem.setEnabled(false);
    }

    public void enableStartMenuItem() {
        startMenuItem.setEnabled(true);
    }

    public void disableStartMenuItem() {
        startMenuItem.setEnabled(false);
    }

    public void actionPerformed(ActionEvent event) {
        if (event.getSource() == setBPMButton) {
            int bpm = Integer.parseInt(bpmTextField.getText());
            controller.setBPM(bpm);
        } else if (event.getSource() == increaseBPMButton) {
            controller.increaseBPM();
        } else if (event.getSource() == decreaseBPMButton) {
            controller.decreaseBPM();
        }
    }

    public void updateBPM() {  

        if (model != null) {
            int bpm = model.getBPM();
            if (bpm == 0) {
                if (bpmOutputLabel != null) {
                    bpmOutputLabel.setText("offline");
                }
            } else {
                if (bpmOutputLabel != null) {
                    bpmOutputLabel.setText("Current BPM: " + model.getBPM());
                }
            }
        }
    }

    public void updateBeat() {
        if (beatBar != null) {
             beatBar.setValue(100);
        }
    }
        }

There is an observer pattern relationship between Model part and View part .

Controller part :
Strategy:

public interface ControllerInterface {
    void start(); 
    void stop();
    void increaseBPM();
    void decreaseBPM();
    void setBPM(int bpm);
}

implement strategy:

public class BeatController implements ControllerInterface {
    BeatModelInterface model; 
    DJView view;

    public BeatController(BeatModelInterface model) {
        this.model = model;
        view = new DJView(this, model);  
        view.createView();
        view.createControls();
        view.disableStopMenuItem();
        view.enableStartMenuItem();
        model.initialize();
    }

    public void start() {                  
        model.on();
        view.disableStartMenuItem();    
        view.enableStopMenuItem();
    }

    public void stop() {
        model.off();
        view.disableStopMenuItem();
        view.enableStartMenuItem();
    }

    public void increaseBPM() {
        int bpm = model.getBPM();
        model.setBPM(bpm + 1);
    }

    public void decreaseBPM() {
        int bpm = model.getBPM();
        model.setBPM(bpm - 1);
    }

    public void setBPM(int bpm) {   
        model.setBPM(bpm);
    }
}

At last we combine MVC together :

public class DJTestDrive {

    public static void main (String[] args) {
        BeatModelInterface model = new BeatModel();
    ControllerInterface controller = new BeatController(model);      
    }
}

--------The end of the example--------
Question :

I could only change the actionperformed part in the view to lambda expression like this :
original:

        menuBar = new JMenuBar();
        menu = new JMenu("DJ Control");
        startMenuItem = new JMenuItem("Start");
        menu.add(startMenuItem);
        startMenuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                controller.start();
            }
        });
        stopMenuItem = new JMenuItem("Stop");
        menu.add(stopMenuItem); 
        stopMenuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                controller.stop();
            }
        });
        JMenuItem exit = new JMenuItem("Quit");
        exit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                System.exit(0);
            }
        });

to lambda expression:

        menuBar = new JMenuBar();
        menu = new JMenu("DJ Control");
        startMenuItem = new JMenuItem("Start");
        menu.add(startMenuItem);
        startMenuItem.addActionListener((ActionEvent event) -> {
            controller.start();
        });
        stopMenuItem = new JMenuItem("Stop");
        menu.add(stopMenuItem); 
        stopMenuItem.addActionListener((ActionEvent event) -> {
            controller.stop();
        });
        JMenuItem exit = new JMenuItem("Quit");
        exit.addActionListener((ActionEvent event) -> {
            System.exit(0);
        });   

Are there any more places I could use lambda expression in this kind of complex example ? or maybe I shouldn't use lambda expression in complex situations like this ?

Thank you so much for your patience .