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Threads join() method

 
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Hello,

I was reading about join() from the tutorial's provided by sun

http://java.sun.com/docs/books/tutorial/essential/concurrency/join.html

It says that join() stops the current thread to stop and join it at the end of other thread and it must wait, till that thread completes
and then the current thread will start resuming its work. But i am confused by this line, what does it mean

"The join method allows one thread to wait for the completion of another. If t is a Thread object whose thread is currently executing,
t.join();"

Does it mean t is the currently running thread?? Please help.


 
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Ben Zaidi wrote:"The join method allows one thread to wait for the completion of another. If t is a Thread object whose thread is currently executing, t.join();"
Does it mean t is the currently running thread??



"t" is a currently running Thread object but the code you call the "t.join()" is the one going to wait till Thread "t" completes.
 
Ben Zaidi
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But doesn't the join() method, cause the current thread of execution to stop till the other has completed.

if t is the currently running thread, shouldn't it mean that t should stop execution and let other thread complete the execution first?
 
Vijitha Kumara
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Ben Zaidi wrote:if t is the currently running thread, shouldn't it mean that t should stop execution and let other thread complete the execution first?



No that means join the Thread "t" so the code calling "t.join()" (which is run by another thread) waits till Thread t completes.
 
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Perhaps this is lot clearer

java.lang.Thread.join()

Waits for this thread to die.

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



The currently executing thread(one which is executing the t.join() instruction) will wait for the 't' instance to complete.
 
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When you call t.join(), the current thread will stop and wait until thread t has finished executing. When t has finished, the current thread will resume executing.

So it's really simple: if you call t.join(), you make the current thread wait until thread t has finished.
 
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