Thread Sleeping problem

[saravana.T kumar]

Hi,
public class test extends Thread
{
public void run()
{
try{
for(int i=0;i<5;i++)
System.out.println(Thread.currentThread() + " " + i);
Thread.sleep(10000);
}
catch(Exception e){}
}

public static void main(String arg[]) throws Exception
{
Thread t=new Thread(new test(),"joe");
Thread t1=new Thread(new test(),"jo");
t.start();
t1.start();
}}

The problem in this code is that the sleep method is not suspending the execution even though i read that its a static method..

[Paul Napauleon]

Hi,

this one is pretty tricky I think. The issue is that the sleep of both threads is invoked at the end, because the thread run concurrently and the sleep is not in the loop.

Thread one will loop and print and then sleeps, but in the mean time thread 2 does the same. When you put a print statement after the sleep statement, you will see that the threads do actually sleep.

[Murali Kakarla]

By printing timestamps it would be clear.

Try this code:

import java.util.Date;
 
public class Thread03 extends Thread {
  public void run() {
    try {
      for (int i = 0; i < 5; i++)
        System.out.println(Thread.currentThread() + " " + i);
      Date d1 = new Date();
      System.out.println("Before sleep: " + d1.toString() + " Thread Name: " + Thread.currentThread().getName());
      Thread.sleep(10000);
      d1 = new Date();
      System.out.println("After sleep: " + d1.toString() + " Thread Name: " + Thread.currentThread().getName());
    } catch (Exception e) {
    }
  }
 
  public static void main(String arg[]) throws Exception {
    Thread t = new Thread(new Thread03(), "joe");
    Thread t1 = new Thread(new Thread03(), "jo");
    t.start();
    t1.start();
  }
}

When you run this code o/p will be something like this:

Thread[joe,5,main] 0
Thread[joe,5,main] 1
Thread[joe,5,main] 2
Thread[joe,5,main] 3
Thread[joe,5,main] 4
Thread[jo,5,main] 0
Thread[jo,5,main] 1
Thread[jo,5,main] 2
Thread[jo,5,main] 3
Thread[jo,5,main] 4
Before sleep: Tue Jul 24 17:31:11 IST 2007 Thread Name: joe
Before sleep: Tue Jul 24 17:31:11 IST 2007 Thread Name: jo
After sleep: Tue Jul 24 17:31:21 IST 2007 Thread Name: joe
After sleep: Tue Jul 24 17:31:21 IST 2007 Thread Name: jo

And here we can see that both threads actually slpet for 10 seconds.

Murali...

[Deepinder Singh]

The Thread.sleep() method works for the currently executing thread...and I think the code is working as expected...

[Bob Ruth]

Yup. That code as written will write the message out 5 times, quick like a bunny rabbit, and then sleep for ten seconds....once. If you wanted (message and a ten second sleep) five times.... you will need curly braces around the block after the "for()".

[saravana.T kumar]

Thanks everyone for your explanations and Examples