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Launch batch file from java?

Tempora Telora
Ranch Hand

Joined: Jun 20, 2005
Posts: 83
I have been trying to launch the batch file using :

String cmd = "c:\\here.bat";
Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec(cmd);

Nothing fires though. When I put notepad where cmd is it launches just fine. But when I keep my cmd the same and try and launch it runs the command and keeps running my java code. The bat file should have a printout screen where it displays certain values. This is not happening.

In my code I do have try/catch blocks.

Any ideas?

Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

The standard input and output of the process are connected to OutputStreams and InputStreams, respectively, that you can get from the Process object returned by the exec() command; they're not connected to the terminal. If you want the output of your batch file to be printed, then you have to use getInputStream() to get the process's output from the Process object, and then in your Java code read the data and print it yourself.

The reason you can see Notepad is because, of course, Notepad doesn't use its standard output -- instead it throws up a GUI.

[Jess in Action][AskingGoodQuestions]
Tempora Telora
Ranch Hand

Joined: Jun 20, 2005
Posts: 83
What I am saying though is that I feel that my batch file is not being launched. Is my call wrong?
fred rosenberger
lowercase baba

Joined: Oct 02, 2003
Posts: 11955

why do you think it is not running? is something not done (a file not created, an email not sent) that you think should be? or do you think it's not because you don't see anything on your screen?

if it's the latter, then re-read what Ernest said. the .bat file COULD be running, but if all it does it print something, you're not gonna see it unless you get that InputStream.


i went back and re-read your original post...

what is (most likely) happening is that your script IS running. but the output from your script is not going to the screen, like EFH said. that's why you're not seeing it. it's going to your .bat file's output stream, which is not attatched to your screen. it is effectively going nowhere.

follow EFH's advice. get the stream. read from the stream, and print it out in your java code.
[ October 26, 2006: Message edited by: fred rosenberger ]

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Lucas Lee
Ranch Hand

Joined: Oct 02, 2006
Posts: 53
You should write your Java code like below:
String cmd = "cmd /c c:\\here.bat";
Then the runtime class will run the CMD process for you.
I agree. Here's the link:
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