CODEWITHSUNDEEP
javaprocessruntime.exec
ma.aero
ma.aero

Reputation: 107

Run execute file in Runtime.exec() and get user input

How to run c execute file with user input in Java Runtime().exec(). Without user input in my c program execute file runs in Runtime().exec():

For example: Below c program if n is predefined and it's execute file runs in java runtime()...If n is a user input how to run the execute file?

#include <stdio.h>
#include <time.h>    
#include <unistd.h>
int main()
{
   setbuf(stdout, NULL); //set buffer null
   int i,n;
   scanf("%d",&n);
       for(i=0;i<=n;i++)
   {
    printf("%d\n",i);
    sleep(1); //delay
   }
} //main

Java code ....

import java.io.*; 
import java.lang.Runtime;
import java.lang.*;
import java.io.File;
import java.util.Timer;
import java.util.TimerTask;

public class run3
{
 public static void main(String[] args)
 {
 try
 {
 String[] cmd = {"file path"};
 Process p = java.lang.Runtime.getRuntime().exec(cmd);
 String s;
 BufferedReader stdInput = new BufferedReader(new 
                                          InputStreamReader(p.getInputStream()));
 BufferedReader stdError = new BufferedReader(new  
                                          InputStreamReader(p.getErrorStream()));

    while ((s = stdInput.readLine()) != null)
    {    System.out.println(s);    }

          System.out.println("Done.");
   }//try
  catch (IOException ex) 
  { ex.printStackTrace();   }
 } //void
} //main

Upvotes: 3

Views: 2207

Answers (1)

Stephen C
Stephen C

Reputation: 718738

There are various ways to do this, depending on exactly what you are trying to achieve:

  • The simplest way to do this would be to pass n as a command line argument.

  • You could have the C program read n from its standard input ... and write to it from the Java side using the Process object's getOutputStream method.

  • You could have the C program open "/dev/console" or "/dev/tty" and read n from there. On Windows I believe you can do this in other ways.

OK. Given that, you just need to call p.getInputStream(), write the input to that stream, and close it ... before attempting to read the command's output.

Upvotes: 1

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