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I am executing an .exe-file from java, using the ProcessBuilder class and the Process class. To explain what I am doing:

 builder = new ProcessBuilder(commands);
 builder.redirectErrorStream(true);
 Process process = builder.start();
 process.waitFor();

I just wanted to know, for how long is "waitFor()" waiting? Is it waiting until my .exe is executed, or is it waiting till its execution is finished?

My .exe is a compiled AutoIt-script. That means, that there could be interactions like mouse movements, which take some time. So I need to know if my Java-code execution goes on after calling the .exe or if it is really waiting for it.

What I want to achieve is the rotational execution of two scripts, but I'm afraid, that my Java code is executing the second script while the first one is still running. Has anyone a workaround for this? I am glad for any ideas.

MRazian
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KJaeg
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    I'm quoting the docs: "*Causes the current thread to wait, if necessary, until the process represented by this Process object has terminated. This method returns immediately if the subprocess has already terminated.*". – Maroun Apr 20 '15 at 11:16
  • Have a look at [when-runtime-exec---won-t](https://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html). There is a good description of the `Process.waitFor()` use cases. – MockerTim Dec 28 '17 at 13:26

3 Answers3

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Your current execution thread will be blocked on process.waitFor() until process is terminated (i.e. execution finished). Source here

Also note that if process is already terminated : waitFor() will not be blocked. I don't know if the code you put in your question is exactly what you run... but you must be careful and re-create a new instance of Process for every execution of your script (i.e. not just calling start multiple times on the same Process: it won't work after first execution)

ben75
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  • OK, thanks for giving me more insight. I was unsure how "process" is definied in the docs. I was not sure if "process" means the process of executing just the console commands or if it includes their full execution. – KJaeg Apr 20 '15 at 11:38
5

It will wait till the process is finished. Workaround:

1 Use isAlive()

2 Use waitFor(long timeout, TimeUnit unit) (Only 1.8)

Miss Chanandler Bong
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Evgeniy Dorofeev
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5

Additionally, If there are outputs in the "commands". you should read the standard output and standard error output by stream(process.getErrorStream()) and process.getInputStream()).If not and output or error output be full, the waitfor() would be hanged.

Dovydas Šopa
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Dorleeze
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