swing timer doesn't work properly [closed]

Question

hi there i am working on a project(java memory game) and first of all i am trying to understand that how swing timer works. firstly, i my main class implements ActionListener and ItemListener. and i use timer in actionPerformed(ActionEvent e) if two cards which user selected different pictures then i use timer.start() to give him a couple of seconds to see pictures and then they will be closed again. but if user selects two different pictures they suddenly closed, so i can't see the second picture. i read some tutorials about swing timer but i guess i understood wrongly.by the way i created my to SSCCE, and i will be appreciated if you can help me. thanks anwyway...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.Menu;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.Random;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.border.*;

public class ConcentrationGame4 extends JFrame implements ActionListener, ItemListener{

    private static final long serialVersionUID = 1L;
    private int buttoncounter=0;
    private int counter = 0;
    private JFrame frame;
    private JPanel mainPanel;
    private JPanel buttonPanel;
    private JMenuBar menuBar;
    private JMenu menu;
    private JMenuItem menuItem;
    private int[] arr = new int[16];
    private int i,j;
    private int random;
    private int size = 4;
    private Icon hidden;
    private GameButton buttonFirst;
    private GameButton buttonSecond;
    private Timer timer;

    private Icon img[] = {UIManager.getIcon("OptionPane.errorIcon"),
            UIManager.getIcon("OptionPane.informationIcon"),
            UIManager.getIcon("OptionPane.warningIcon")};

    private Icon iconList[] = new ImageIcon[size];

    public ConcentrationGame4(){
        createArray();
        initComponents();
    }


    private void initComponents(){

        frame = new JFrame("Concentration Game");
        menuBar = new JMenuBar();
        menu = new JMenu("Menu");
        frame.setJMenuBar(menuBar);
        menuBar.add(menu);
        menuItem = new JMenuItem("New Game");
        menu.add(menuItem);
        menuItem = new JMenuItem("Solve");
        menu.add(menuItem);
        menuItem = new JMenuItem("Exit");
        menu.add(menuItem);
        mainPanel = new JPanel(new BorderLayout(5, 5));
        mainPanel.setBorder(new EmptyBorder(4,4,4,4));
        frame.setContentPane(mainPanel);
        buttonPanel = new JPanel(new GridLayout(4,4,5,5));
        buttonPanel.setBackground(Color.green);

        timer = new Timer(2000,this);

        for(i=0; i<4; i++){

            final GameButton button = new GameButton(iconList[i]);
            button.addItemListener(this);
            button.addActionListener(this);
            buttonPanel.add(button);

        }

        mainPanel.add(buttonPanel, BorderLayout.CENTER);
        frame.setSize(300, 300);
        //frame.pack();
        frame.setLocation(300, 300);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    public void itemStateChanged(ItemEvent e){

        GameButton button = (GameButton) e.getItem();

        button.setState();
    }

    public void actionPerformed(ActionEvent e){
        GameButton button = (GameButton) e.getSource();

        if(button.isSelected()){
            buttoncounter++;

            if(buttoncounter==1){
                buttonFirst = (GameButton) e.getSource();
            }
            else if(buttoncounter==2){

                buttonSecond = (GameButton) e.getSource();
                buttoncounter=0;

                    if( checkPairs(buttonFirst,buttonSecond) ) {
                        retirePair(buttonFirst,buttonSecond);
                    }

                    else{   
                        timer.start();
                        falsePair(buttonFirst, buttonSecond);

                    }

            }

    }

    }

    class GameButton extends JToggleButton{

        private static final long serialVersionUID = 1L;
        private Icon icon;

        public GameButton(Icon icon){
            this.icon = icon;
        }

         public void setState() {
                if (this.isSelected() || !this.isEnabled()) {
                    this.setIcon(icon);
                }

                else {
                    this.setIcon(hidden);
                }
            }
        }

    private void retirePair(GameButton a, GameButton b){

        a.setSelected(true);
        a.setEnabled(false);
        b.setSelected(true);
        b.setEnabled(false);

    }

    private void falsePair(GameButton buttonFirst, GameButton buttonSecond){

        buttonFirst.setIcon(hidden);
        buttonFirst.setSelected(false);
        buttonSecond.setIcon(hidden);
        buttonSecond.setSelected(false);
    }

    private boolean checkPairs(GameButton first, GameButton second){
        if(first.getIcon().equals(second.getIcon()))
            return true;
        else
            return false;
    }

    private void createArray(){
        Random rnd = new Random();
        while(i<4){

            random = rnd.nextInt(3)+1;
            if(!includes(random)){
                arr[i]=random;
                iconList[i] = img[random-1];
                i++;
            }
        }
    }

    public boolean includes(int rnd){
        counter=0;
        for(j=0; j<arr.length; j++){

            if(arr[j] == rnd){
                counter++;
                if(counter>1)
                    return true;
            }
        }

        return false;
    }

    /**
     * @param args
     */
    public static void main(String[] args) {

        new ConcentrationGame4();

    }

}

Answer 1

I don't know what you want to do, but you pass this as argument to the Timer constructor. This means that every 2 seconds, the actionPerformed method of this (instance of ConcentrationGame4) will be called. And the first thing that this method does is

GameButton button = (GameButton) e.getSource();

Obviously, this will throw an exception, since the origin of the event won't be a game button, but the timer.

To understand what a Timer does and how it works, it's very simple. You just have to read its api doc : http://download.oracle.com/javase/6/docs/api/javax/swing/Timer.html. This doc will even lead you to a tutorial explaining how they work, with examples.

Answer 2

As an aside, you might want to look at using List<Icon> and List<GameButton>. Such Collections are easy to shuffle in a reliable way. Also, note the difference between an individual GameButton and a collection of them, external to the GameButton class. It's the collection that you'll need to examine when any one button is clicked.

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
import javax.swing.Timer;
import javax.swing.UIManager;

/** @see http://stackoverflow.com/questions/7933424 */
public class ButtonTimer extends JPanel {

    private List<Icon> list = new ArrayList<Icon>();
    private List<GameButton> buttons = new ArrayList<GameButton>();
    private Timer timer = new Timer(1000, new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            createPanel();
        }
    });

    public ButtonTimer() {
        this.setLayout(new GridLayout(1, 0));
        list.add(UIManager.getIcon("OptionPane.errorIcon"));
        list.add(UIManager.getIcon("OptionPane.informationIcon"));
        list.add(UIManager.getIcon("OptionPane.warningIcon"));
        list.add(UIManager.getIcon("OptionPane.questionIcon"));
        createPanel();
        timer.start();
    }

    private void createPanel() {
        Collections.shuffle(list);
        this.removeAll();
        for (Icon icon : list) {
            GameButton gb = new GameButton(icon);
            buttons.add(gb);
            this.add(gb);
        }
        this.revalidate();
    }

    class GameButton extends JToggleButton {

        private Icon icon;

        public GameButton(Icon icon) {
            super(icon);
            this.icon = icon;
        }
    }

    private void display() {
        JFrame f = new JFrame("ButtonTimer");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ButtonTimer().display();
            }
        });
    }
}

Answer 3

An example of using a Swing Timer to pause action for xxx seconds:

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

@SuppressWarnings("serial")
public class QuickTimerEg extends JPanel {
   private static final int TIMER_DELAY = 2000;
   private boolean buttonsWorking = true;
   private JButton btn1 = null;
   private JButton btn2 = null;
   private Timer swingTimer;

   public QuickTimerEg() {
      ActionListener btnListener = new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            btnActionPerformed(e);
         }
      };
      setLayout(new GridLayout(4, 4));
      for (int i = 0; i < 4; i++) {
         for (int j = 0; j < 4; j++) {
            JButton button = new JButton("   ");
            button.addActionListener(btnListener);
            add(button);
         }
      }
   }

   private void btnActionPerformed(ActionEvent e) {
      if (!buttonsWorking) {
         return;
      }
      JButton button = (JButton)e.getSource();
      button.setBackground(Color.blue);
      button.setEnabled(false);
      if (btn1 == null) {
         btn1 = button;
      } else {
         buttonsWorking = false;
         btn2 = button;
         swingTimer = new Timer(TIMER_DELAY, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
               btn1.setBackground(null);
               btn2.setBackground(null);
               btn1.setEnabled(true);
               btn2.setEnabled(true);
               btn1 = null;
               btn2 = null;
               buttonsWorking = true;               
            }
         });
         swingTimer.setRepeats(false);
         swingTimer.start();
      }
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("QuickTimerEg");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new QuickTimerEg());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

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