How to know if other threads have finished?

Question

I have an object with a method named StartDownload(), that starts three threads.

How do I get a notification when each thread has finished executing?

Answer 1

You can interrogate the thread instance with getState() which returns an instance of Thread.State enumeration with one of the following values:

*  NEW
  A thread that has not yet started is in this state.
* RUNNABLE
  A thread executing in the Java virtual machine is in this state.
* BLOCKED
  A thread that is blocked waiting for a monitor lock is in this state.
* WAITING
  A thread that is waiting indefinitely for another thread to perform a particular action is in this state.
* TIMED_WAITING
  A thread that is waiting for another thread to perform an action for up to a specified waiting time is in this state.
* TERMINATED
  A thread that has exited is in this state.

However I think it would be a better design to have a master thread which waits for the 3 children to finish, the master would then continue execution when the other 3 have finished.