You should look into the arts of concurrent programming, and
specifically barrier synchronization.

-Deniz Dogan

Depending on how your threads are arranged, you can use a CountdownLatch  
or a CyclicBarrier from the java.util.concurrent package.

Dan.

While you could use general barrier techniques, there may be a simple
alternative for your specific situation. Once the threads in question
have been created, pass a list of references to them to a additional
"join" thread.

The "join" thread just calls each Thread object's join method. When the
last join call completes, all the threads have finished their run
methods, and the "join" thread executes the "some actions".

The "join" thread can be the thread that created them if it has no other
work it needs to do afterwards.

You need the general barrier approach if you need the "some actions" to
run in the individual threads after each has completed the substance of
its work but before the actual return.

Patricia