A problem with synchronizing threads.
Hello, I have some code listed below. Eventually I will have 4 threads, 3 of which will make up a counter (hours, minutes, seconds).
At the moment I simply wish to get some functionality from my program before making it more complex. I am trying to pass a value ("Test String") into a JLabel and have set up a synchronized block that takes the argument and updates the field. This block has a boolean condition controlled by the controller, ever second this is set to true.
The problem I am having is that none of the threads are updating the screen. I have tried system.out to test and they are getting to the wait block but no further.
Can anyone spot what I am doing wrong. For now I will just post the main class, I can supply the other 3 if you like but I feel the problem lies with this one.
import java.awt.FlowLayout;
import javax.swing.*;
publicclass ClockDisplay
{
privateint hours = 0;
privateint minutes =0;
privateint seconds = 0;
boolean okToSend=false;
private JFrame myFrame =new JFrame();
private JTextField textField =new JTextField(8);
private ClockDisplay()
{
}
publicvoid startUp()
{
myFrame.setLayout(new FlowLayout());
myFrame.add(textField);
myFrame.setSize(300, 300);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setVisible(true);
}
publicsynchronizedvoid changeText(String s)
{
boolean okToSend =false;
try
{
while(!okToSend)
{
System.out.println(s);//ignore
wait();
}
okToSend =false;
textField.setText(s);
}
catch(InterruptedException ex){}
}
publicsynchronizedvoid allowOutput()// Sys outs show the controller enters here
{
okToSend =true;
notify();
}
//Singleton Class
privatestaticclass SingletonHolder
{
privatestatic ClockDisplay instance =new ClockDisplay();
}
publicstatic ClockDisplay getInstance()
{
return SingletonHolder.instance;
}
}
Cheers
Mike
[4217 byte] By [
kikemellya] at [2007-10-3 10:39:23]
Hello again.
I am having some more trouble with threads. I have a start class and a threads class as well as the one below. The start class creates 3 new threads from the the threads class and deploys them on the class below. The problem I am having is that the seconds counter dosent get passed 3. The threads are locking in some way and I cant work out how.
My code is below, can anyone spot what I am doing wrong?
package com.mk.clock;
import java.awt.FlowLayout;
import javax.swing.*;
public class ClockDisplay
{
private int hours = 0;
private int minutes =0;
private int seconds = 0;
boolean okToSend3;
boolean okToSend2;
boolean okToSend1;
private JFrame myFrame = new JFrame();
private JTextField textField1 = new JTextField(2);
private JTextField textField2 = new JTextField(2);
private JTextField textField3 = new JTextField(2);
private ClockDisplay()
{
}
public void startUp()
{
myFrame.setLayout(new FlowLayout());
myFrame.add(textField1);
myFrame.add(textField2);
myFrame.add(textField3);
myFrame.setSize(300, 300);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setVisible(true);
}
public synchronized void changeText()
{
try
{
Thread.sleep(1000);
seconds++;
textField3.setText(String.valueOf(seconds));
System.out.println(seconds);
if (seconds >59)
{
seconds=0;
allowUpdateT2();
}
}
catch(InterruptedException ex){}
try
{
while(!okToSend2)
{
wait();
}
textField2.setText(String.valueOf(minutes++));
okToSend2=false;
if(minutes >59)
{
minutes=0;
allowUpdateT1();
}
}
catch(InterruptedException ex){}
try
{
while(!okToSend1)
{
wait();
}
textField1.setText(String.valueOf(hours++));
okToSend1=false;
}
catch(InterruptedException ex){}
}
public synchronized void allowUpdateT3()
{
okToSend3 = true;
notify();
}
public synchronized void allowUpdateT2()
{
okToSend2 = true;
notify();
}
public synchronized void allowUpdateT1()
{
okToSend1 = true;
notify();
}
//Singleton Class
private static class SingletonHolder
{
private static ClockDisplay instance = new ClockDisplay();
}
public static ClockDisplay getInstance()
{
return SingletonHolder.instance;
}
}
I deploy the threads on the "change text" method. I know I could create 3 different methods for each textbox and 3 different thread classes for each textbox but surely there is an easier way.
Any help would be great.
Mike
p.s. do i need 3 different try/catch blocks our could I use one for all text boxes?
.
here si sthe rest of my code;
public class ThreadClock
{
static ClockDisplay cd = ClockDisplay.getInstance();
public static void main(String[] args)
{
Thread h = new Thread(new WorkerThread("hours"));
Thread m = new Thread(new WorkerThread("minutes"));
Thread s = new Thread(new WorkerThread("seconds"));
cd.startUp();
s.start();
m.start();
h.start();
}
}
and
public class WorkerThread implements Runnable
{
static ClockDisplay cd = ClockDisplay.getInstance();
String name;
public WorkerThread(String name)
{
this.name = name;
}
public void run()
{
cd.changeText();
}
}
can anyone give me some sort of advice, even if its "**** off"?
