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I'm unsure how to start an external application (specifically on Windows) through Java code. I'm not planning on using this Java code for Mac/Linux, so let's focus on the Windows code.

What I've Done

I've been researching this question for the last two days, and I still have not found an answer. I easily found the Runtime.getRuntime().exec() method, but the thing is I cannot find information on launching a Batch (.bat) file from my local workspace in IntelliJ Idea.

What I'm Asking

I would just like to know how to execute a local Batch file in my workspace (at a folder like com.example.batch) and/or how to execute a (.exe) or (.bat) with the direct file address. (For example the Defragment and Optimize Drives (.exe) for Windows: C:\WINDOWS\system32\dfrgui.exe)

Thanks to all in advance, I've been dying for this answer.

VenHayz
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  • Have you tried something like the answer for [this question](http://stackoverflow.com/questions/615948/how-do-i-run-a-batch-file-from-my-java-application)? – D.B. Jun 25 '16 at 02:56

2 Answers2

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First, you should be using ProcessBuilder to execute external programs, for an easier-to-use interface than Runtime.getRuntime().exec().

Second, to execute a .bat file, all you have to do is execute cmd.exe and pass the batch file name in the /C option. Note that when you run a batch file you are starting a DOS cmd processor and telling it to run the batch file instead of reading from the terminal. Therefore, the batch file must be in a location that is accessible to cmd.exe. Therefore it cannot be inside a jar file containing your Java program. If it is necessary to distribute it in the jar you will have to copy it to the filesystem somewhere.

Jim Garrison
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Have you read the essential Runtime.exec() article?

Page 2 of this article lists a common pitfall: Runtime.exec() is not a command line.

.bat files are not executables. They are collections of instructions. Like shell scripts in Linux, you need something to actually execute these instructions.

Your executable in this case is cmd.exe, which will take /C and com.example.batch as its arguments:

Runtime.getRuntime().exec(new String[] { "cmd.exe", "/C", "com.example.batch"});

As a side note, check out the ProcessBuilder class. It's much nicer than Runtime. And yes, all the rules in the Runtime article apply to ProcessBuilder.

Jake
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  • Great answer. I chose it because you focused on one topic you gave complete detail into. Thanks! – VenHayz Jun 25 '16 at 04:35