Are you good at threads?

Question

HI!
I have problems with java and threading!
I have made a clock with two threads. It almost works but if i, start it and stop it, i can't start it again.
I can't fint the fault!!
can anyone help??
Stian
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class klokke3 extends JFrame implements ActionListener{
    private JPanel en = new JPanel();
    private JButton startklokke,stoppklokke;
    //private int settigang;
    private Second sekund;
    private Minute minute;
    private TickTock minuteTick;
     public static void main(String[] args) {
        klokke3 frame = new klokke3();
        frame.setSize(500,300);
        frame.init();
        frame.show();
    public void init() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        getContentPane().add(en); //ma legge panelet i contentpane for at grafik skal vise
        TextField showSeconds = new TextField(20); //oppretter textfields
        en.add(showSeconds);
        showSeconds.setEditable(false);//far ikke lav a skrive i textfield
        TextField showMinutes = new TextField(20);
        en.add(showMinutes);
        showMinutes.setEditable(false);//far ikke lav a skrive i textfield
        startklokke = new JButton("Start klokke");
     en.add(startklokke);
        startklokke.addActionListener(this);
        stoppklokke = new JButton("Stopp/nullstill");
     en.add(stoppklokke);
        stoppklokke.addActionListener(this);
        //en.add(stoppklokke);
        minuteTick = new TickTock();
         minute = new Minute(showMinutes, minuteTick);
         minute.start();
         sekund = new Second(showSeconds, minuteTick);
        //sekund.start();
    public void actionPerformed(ActionEvent e) {
    if (e.getSource() == stoppklokke) {
        sekund.pleasestop();
        //minute.pleasestop2();
    if (e.getSource()==startklokke){
        sekund.start();
class Second extends Thread {
    private int seconds = 0;
    private boolean quit;
    private TextField showSeconds;
    private TickTock minuteTick;
    public Second(TextField showSeconds, TickTock minuteTick) {
        this.showSeconds = showSeconds;
        this.minuteTick = minuteTick;
    public void run() {
        quit=true;
        while(quit) {
            try {
                Thread.sleep(1000);
            catch (InterruptedException e) {
                System.err.println("Exception");
            if(seconds == 59) {
                minuteTick.tick();
                seconds = 0;
            else seconds++;
            showSeconds.setText(seconds + " seconds");
    public void pleasestop(){
        quit=false;
        showSeconds.setText( " ");//Dersom knappen er trykka blanker vinduet
   // public void st(){
   //     quit=true;
class Minute extends Thread {
    private boolean quit2;
    private int minutes = 0;
    private TextField showMinutes;
    private TickTock minuteTick;
    public Minute(TextField showMinutes, TickTock minuteTick) {
        this.showMinutes = showMinutes;
        this.minuteTick = minuteTick;
    public void run() {
        quit2=true;
        while(quit2) {
            minuteTick.waitForTick();
            if (minutes == 59) {
                minutes = 0;
            else
                minutes++;
            showMinutes.setText(minutes + " minutes");
        public void pleasestop2(){
         quit2=false;
         showMinutes.setText( " ");//Dersom knappen er trykka blanker vinduet
         //quit2=true;
     //   public void st2(){
     //       quit2=true;
class TickTock {
    private boolean tickHappens = false;
    public synchronized void waitForTick() {
        while (!tickHappens)
            try {
                wait();
            catch (InterruptedException e) {
                System.err.println("Exception");
        tickHappens = false;
    public synchronized void tick() {
        tickHappens = true;
        notify();
}

Answer 1

But now i got a new problem.
I f i press the startbutton many times. several
clock's start and i only want one to startYou need to post your new code.
A comment about your variables.
1. 'quit' means 'stop' you loop on quit == true. That's a little confusing.
2. You use the name quit1 in one of your classes. There's no reason to name it differently. It's just annoying.