Java Swing blinking button sequence

Question

I'm trying to make a remedial simon says like game using Swing (Jframe/jbuttons/grid setup). At the moment I can't figure out how to get a sequence of buttons to flash. I can't run a thread through my swing timer since actionPerformed is non static, I don't know what TODO. I'd really appreciate if someone could take a glance at my code and offer insight. package MemoryGame;

import java.util.logging.Level; import java.util.logging.Logger; import javax.swing.; import java.awt.event.; import java.awt.*; import java.util.Random; import java.lang.InterruptedException;

public class GUI {

static int seconds = 0;
static int buttonIndex = 0;
int[] movesArr = new int[10];
int numberOfButtons  = 18;
Thread thread = new Thread();
boolean[] logicArr   = new boolean[numberOfButtons];
JFrame frame         = new JFrame("Memory Builder");
JPanel buttonPanel   = new JPanel();
JPanel panelBot      = new JPanel(new BorderLayout());
GridLayout grid      = new GridLayout(0, 3) {{ setHgap(8); setVgap(8); }};
JLabel scoreLabel    = new JLabel("Score");
static JLabel timeLabel     = new JLabel("0");
JButton button[]     = new JButton[numberOfButtons];
Listener listener    = new Listener();
Timer displayTimer   = new Timer(1000, listener.new DisplayTimeListener());
Timer buttonTimer    = new Timer(300, listener.new ButtonDisplayListener());
Color buttonColor;

public GUI() {

    //Setup frame
    frame.setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Create button panel
    buttonPanel.setLayout(grid);
    buttonPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    addButtonPanel();

    //create label pane
    panelBot.add(timeLabel, BorderLayout.WEST);
    panelBot.add(scoreLabel, BorderLayout.EAST);
}

public void centerFrame() {

    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
    frame.setLocation((dim.width - frame.getWidth()) / 2,
            (dim.height - frame.getHeight()) / 2);
}

public void addButtonPanel() {

    for (int i=0; i < button.length; i++){
        button[i] = new JButton();
        button[i].addActionListener(listener.new ButtonListener());
        button[i].setText("Button " + (i + 1));
        button[i].setName(new Integer(i).toString());
        buttonPanel.add(button[i]);
    }

    buttonColor = button[0].getBackground();
}


public void createGUI() {
    frame.add(buttonPanel);
    frame.add(new JSeparator());
    frame.add(panelBot);        
    frame.pack();
    centerFrame();
    buttonPanel.setVisible(true);
    frame.setVisible(true);
    displayTimer.start();
    runGame();
}

public void runGame() {

    boolean isGameOver = false;
    int difficulty = 3;
    Random random = new Random();

    //generate and display random sequence
    for(int i = 0; i < difficulty; i++) {
        movesArr[i] = random.nextInt(numberOfButtons);
        System.out.println(movesArr[i]);
    }
    new BlinkThread().run();

}



public static void main(String[] args) {
   SwingUtilities.invokeLater(new Runnable(){
       public void run(){
           new GUI().createGUI();
        }
   });
}

public class Listener {


boolean flag = true;

public class ButtonDisplayListener implements ActionListener {

    public void actionPerformed(ActionEvent e) {
        if (flag){
           button[buttonIndex].setBackground(Color.red);
           flag = !flag;
        }
        else button[buttonIndex].setBackground(buttonColor);

    }
}

public class DisplayTimeListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        GUI.timeLabel.setText(new Integer(seconds++).toString());
    }
}

public class ButtonListener implements ActionListener {

    public void actionPerformed(ActionEvent e) {
    }
}

}

class BlinkThread implements Runnable { public void run(){

     for(int i: movesArr){
        try{
            Thread.sleep(200);
            System.out.println("echo");
            button[i].setBackground(Color.RED);
            Thread.sleep(200);
            button[i].setBackground(buttonColor);
        }
        catch(Exception ex){}
    }

 }

} }

Answer 1

You can create your own thread (or, rather, a Runnable) that flashes the buttons and sleeps between calls, e.g.

class FlashThread implements Runnable {
    private int[] indices;
    private int sleepTime;
    ... suitable constructor
    public void run() {
        for (int i : indices) {
            buttonOn(i);
            Thread.sleep(sleepTime);
            buttonOff(i);
            Thread.sleep(sleepTime);
        }
    }
}

That should do the trick.

Alternatively, you can create a timer and add an ActionListener to it (similar to what you are doing with the ButtonDisplayListener etc) that does that flashing.

By the way, don't create a new Random object each time through the loop in runGame(). Generate it once (preferably as an instance variable rather than a local) then use it multiple times. Random object generation is (potentially) expensive and generating a bunch of Random objects somewhat defeats the purpose of the Random class.

Answer 2

As suggested by @Cameron Skinner, this example uses javax.swing.Timer to blink buttons for a simple matching game. Timer is particularly convenient for this, as its action event handler executes on the event-dispatching thread.