CODEWITHSUNDEEP
java
Suresh Kumar
Suresh Kumar

Reputation: 95

runtime.exec() taking infinite time to execute code

I want to execute a command which takes 2 arguments. 1.input file name 2.output file name.

The command is sixV1.1 outputFile.txt The code is:

   String cmd= "sixV1.1 <inputFile.txt >outputFile.txt";
   Process p=Runtime.getRuntime().exec(cmd);
   int retValue=p.waitFor();

when the i run above code,it is taking infinite time. Is it possible to give <, > charecters in cmd .Please suggest me....

Upvotes: 2

Views: 1747

Answers (2)

Alex
Alex

Reputation: 18532

There's a fantastic blog post by Michael C. Daconta about successful command line calls using Runtime in Java. It's not as easy as you might think!

The following code extract from that blog post describes "MediocreExecJava", a class that successfully runs a program using Runtime.exec() and manages its input and output without hanging. I've used it before and it works. I highly recommend reading the post to understand why!

import java.util.*;
import java.io.*;
public class MediocreExecJavac
{
    public static void main(String args[])
    {
        try
        {            
            Runtime rt = Runtime.getRuntime();
            Process proc = rt.exec("javac");
            InputStream stderr = proc.getErrorStream();
            InputStreamReader isr = new InputStreamReader(stderr);
            BufferedReader br = new BufferedReader(isr);
            String line = null;
            System.out.println("<ERROR>");
            while ( (line = br.readLine()) != null)
                System.out.println(line);
            System.out.println("</ERROR>");
            int exitVal = proc.waitFor();
            System.out.println("Process exitValue: " + exitVal);
        } catch (Throwable t)
          {
            t.printStackTrace();
          }
    }
}

Upvotes: 0

rgerganov
rgerganov

Reputation: 2232

The right way to do input/output redirection when you start a process in Java is to write/read from the process's streams:

Process p = Runtime.getRuntime().exec("sixV1.1");
InputStream is = p.getInputStream();
// read from is and write to outputFile.txt
OutputStream os = p.getOutputStream();
// read from inputFile.txt and write to os

Upvotes: 1

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