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Making Runtime.exec() wait

Posted on 2004-08-01
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Last Modified: 2009-04-29
The point of this thread is really that I feel like I owe Giant2 some more points for helping beyond what was needed... Others who wish to answer this question, though, see here for the details of my problem (I am willing to split points): http://www.experts-exchange.com/Programming/Programming_Languages/Java/Q_21074134.html#11674022

Though the details are at the link above, I will summarize the issue:
I am using Runtime.getRuntime().exec("javac File.java") to compile a java source file. However, I later JAR the file, so I need the Runtime command to finish compiling before continuing in the program (what it does otherwise is simply starts the compiling process alongside the rest of my program and does both at once).

Now, if I can get a code example I'll award the points and be off to finish my program!
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Question by:CI-Ia0s
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11 Comments
 
LVL 9

Accepted Solution

by:
keteracel earned 160 total points
ID: 11687850
You just want a waitFor() in there:

Process proc = Runtime.getRuntime().exec("javac File.java");
proc.waitFor();
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LVL 86

Expert Comment

by:CEHJ
ID: 11689035
Depends whether you want to do it in one thread or not. You can use waitFor if so. If you're using more than one thread and are compiling\jarring asynchronously, you need to use some form of semaphore
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LVL 3

Author Comment

by:CI-Ia0s
ID: 11689505
It's one thread, and it's working. :)

Keteracel, I'm giving you the majority of the points for your example. I'm just waiting for Giant2 because I do owe him something for his help on this in the other thread. As soon as he posts here I'll split 'em up and dish 'em out.
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LVL 86

Expert Comment

by:CEHJ
ID: 11689532
>>It's one thread, and it's working. :)

Oh - from your other Q it looked like more than one thread ;-)
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LVL 3

Author Comment

by:CI-Ia0s
ID: 11689545
Well... I am running several threads, but the jarring and javacing occur in the same thread. Plus, I'd think waitFor would still work anyway... Java waits to finish any process I call before moving on to the in the thread, right? (i.e. I call method Encrypt() from class EncryptData and it finishes that before continuing with the rest of the program).

Anyway, waiting on Giant2 now...
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LVL 86

Expert Comment

by:CEHJ
ID: 11689576
>>but the jarring and javacing occur in the same thread

OK

>>Java waits to finish any process I call before moving on to the in the thread, right?

Yes

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LVL 92

Expert Comment

by:objects
ID: 11689766
If you're interested here's an example that'll post your command output to a swing text area

http://www.objects.com.au/java/examples/util/SwingExec.do
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LVL 3

Author Comment

by:CI-Ia0s
ID: 11690023
Cool. I was wondering how to get to that info... anyway, thanks. Now where is Giant2!?!?!
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LVL 12

Assisted Solution

by:Giant2
Giant2 earned 140 total points
ID: 11691188
>Now where is Giant2
Sorry, I was out of office.
I believe the answer I gave at the post (Q_21074134.html#11674022) was correct:

I told in the that post:
>yes. You can use the waitFor method over the Process you use to start the javac.

Bye, Giant.
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LVL 3

Author Comment

by:CI-Ia0s
ID: 11694732
Yup, it was. I just haven't worked with the Process class before and needed a code example. (I can see why you thought one wasn't necessary). ;)

You have both been awarded points. Thanks for your help!
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LVL 12

Expert Comment

by:Giant2
ID: 11694763
Thank you.
:-)
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