why this error

[arun mahajan]

Hi,
I am getting the error "java.lang.IllegalMonitorStateException: current thread not owner". can somebody help me to get rid of it?
regards,
Arun
Code:-
******
import java.io.*;
public class check
{
public static void main(String[] args)
{
check xx = new check();
a x = new a(xx);
b y = new b(xx);
try
{
y.start();
}catch(Exception e)
{
System.out.println("Error in start x: "+e);
}
try
{
x.start();
}catch(Exception e)
{
System.out.println("Error in start x: "+e);
}
}
}
class a extends Thread
{
public void run()
{
for(;
{
try
{
System.out.println("Into A");
wait(1*1000);
notifyAll();
}catch(Exception e)
{
System.out.println("Error in a: "+e);
}
}
}
}
class b extends Thread
{
public void run()
{
for(;
{
try
{
System.out.println("Into B");
wait(5*1000);
notifyAll();
}catch(Exception e)
{
System.out.println("Error in b: "+e);
}
}
}
}

[Roy Ben Ami]

first of all the a and the b constrcutors should look like this or ir wont compile:
a x = new a(); //(no xx inside)
b y = new b(); //(no xx inside)
next, when u use wait or notify calls they need to be in synchronized blocks or methods to ensure that the thread owns the objects lock.
so just add the synchronized keyword to each run method like this:
public synchronized void run()

[arun mahajan]

Yes it works with synchronized keyword.
Thanks a lot.
Arun