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running a program from a java application

3 replies. Most recent reply: Feb 27, 2002 3:42 AM by Akhil

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chan

Posts: 2
Nickname: champion
Registered: Feb, 2002

running a program from a java application

Posted: Feb 25, 2002 2:31 PM

I wrote this small program to run the date command within the java application.
import java.lang.*;
import java.io.*;
class rundate {
public static void main(String[] args) throws IOException {
String dateCommand = "date";
rundate champ = new rundate();
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(dateCommand);

}
}

This compiles and runs. Now is this suposed to actually run the date command so i see it
on the screen? Because there is no output on the screen? If so please help me out, or tell me how I could. Thanks

Re: running a program from a java application

Posted: Feb 25, 2002 3:12 PM

Posted by: Bill Venners Posts: 2284 / Nickname: bv / Registered: Jan, 2002

The output of the process is written back to your Java app. You can grab it via the Process object's getInputStream method, then print it to the standard output yourself. Something like:

Process proc = rt.exec(dateCommand);
bis = new BufferedInputStream(proc.getInputStream());

Then just read from bis and write to the standard output.

Re: running a program from a java application

Posted: Feb 25, 2002 11:55 PM

Posted by: Matt Gerrans Posts: 1153 / Nickname: matt / Registered: Feb, 2002

Actually, assuming you are running Windows/DOS, I think the problem is that date is not program, but an internal command of the command interpreter (command.com, or cmd.exe depending on your Windows platform -- look at the COMSPEC environment variable).

You could instead try running "command /c echo.|date" instead, or create a batch file and call that. The reason I added the "echo.|" part is that date will sit there and wait for you to enter a new date without it.

Re: running a program from a java application

Posted: Feb 27, 2002 3:42 AM

Posted by: Akhil Posts: 3 / Nickname: akhilnagpa / Registered: Feb, 2002

I am posting a program i wrote sometime back..i think it can help you.
///////////////////////////////////////////////////////
import java.io.*;
public class Test
{
public static void main(String args[])
{
try
{

//Process p = Runtime.getRuntime().exec("D:\\Akhil-Kiwi\\Kiwi2.5-31may\\kiwiClient\\runclient .bat");
Process p = Runtime.getRuntime().exec("E:\\Apache Tomcat 4.0\\bin\\startup.bat");
BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
bw.write("1");
bw.flush();
String line;
while ((line = br.readLine()) != null)
{
System.out.println(line);
}
br.close();
bw.close();

System.out.println(p.exitValue());

}catch(Exception e)
{
System.out.println("exception Occured");
e.printStackTrace();
}
}
}

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