how to use join( )

[ankur rathi]

public class ThreadTest {

public static void main(String[] args) {

HasRun h  = new HasRun();
Thread t1 = new Thread(h,"A");
Thread t2 = new Thread(h,"B);
t2.setPriority(Thread.MAX_PRIORITY);
t1.setPriority(Thread.MIN_PRIORITY);
t1.start();
t2.start();
}
 
}
 
class HasRun implements Runnable {

public void run() {
for(int i=0; i<=1000; i++) {
System.out.println(Thread.currentThread().getName()+" "+i);
}
}

}
 

In this program , I want to join t2 thread ( fast one ) into t1 or in other word I want that t1 should finish first & then t2 .

how can I do this ?

thanks .

[Jeroen Wenting]

Do you want t2 to join t1 or do you want the application to join t1 before it even starts t2?

If the former you need to have a reference to t1 inside t2 and call join in t2.
If the latter, you call t1.join(); before you call t2.start();

[ankur rathi]

Originally posted by Jeroen Wenting:
Do you want t2 to join t1 or do you want the application to join t1 before it even starts t2?

If the former you need to have a reference to t1 inside t2 and call join in t2.
If the latter, you call t1.join(); before you call t2.start();

application means main thread , right . so yes I can join it like t1.join() after t1.start() , that is solving my purpose ... because now t2 will start execution after t1 will get completed .


Jeroen , can you explain first one with some code .. please
thanks a lot .

[Jeroen Wenting]

Sure.
You'll need to either modify your Runnable a bit first though.

public class ThreadTest {
public static void main(String[] args) {
HasRun h  = new HasRun(null);
Thread t1 = new Thread(h,"A");
HasRun h2 = new HasRun(t1);
Thread t2 = new Thread(h2,"B);
t2.setPriority(Thread.MAX_PRIORITY);
t1.setPriority(Thread.MIN_PRIORITY);
t1.start();
t2.start();
} 
} 
 
class HasRun implements Runnable {
private Thread waitFor;
HasRun(Thread t) {
waitFor = t;
}

public void run() {
if (waitFor != null) {
waitFor.join();
}
for(int i=0; i<=1000; i++) {
System.out.println(Thread.currentThread().getName()+" "+i);}
}
 
}

Now t2 will wait until t1 is done. t1 will wait for nothing because its waitFor Thread is null.

[ankur rathi]

superb logic
thanks a lot .

[ankur rathi]

Hi jaroen ,

Can you please extends this code to use wait() , notify() & notifyAll() mrthod & explain ... please .

thanks a lot .