Javadoc wrote:
join
public final void join()
throws InterruptedException
Waits for this thread to die.

Throws:
InterruptedException - if another thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.

A call to join() Guaranteed to cause the current thread to stop executing until the thread it joins with (in other words, the thread it calls join() on) completes, or if the thread it's trying to join with is not alive, however, the current thread won't need to back out.