How to display the output of an executed command line program?

Question

I have a command line Java program which i unfortunately cannot modify for certain integrity reasons, I am providing a GUI for this program and i got it all covered except that i am unable to provide notifications about completion of processes to the user as the program prints data to command line using System.out.println() , I designed the UI using net beans and it resides in a separate file , so how can i do this..?

Tim Büthe · Accepted Answer · 2012-08-06 19:06:30Z

3

Are you using Runtime.exec to execute the program? Then you can get the output stream as well like this:

Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java yourOtherProgram.jar");
InputStream stdin = proc.getInputStream();

If you're calling some method directly, you could redirect System.out like this:

PrintStream out = ...;
PrintStream err = ...;

System.setOut(out);
System.setErr(err);

ThatOtherProgram foo = new ThatOtherProgram();
foo.main(new String[0]);

EDIT

You could then use the Scanner to scan the input and do something with it.

edited Aug 6, 2012 at 19:06

answered Aug 6, 2012 at 15:31

Tim Büthe

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2 Comments

Riddler Over a year ago

Thanks for your help.. I re implemented the program using runtime.exec but i am still working on how to dynamically provide notifications based on the stream.. Thank you for your effort..

Tim Büthe Over a year ago

You could use the Scanner class to do that.

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