Controlling external programs from Java

Question

Hi,
I try to invoke an external command-line program in Windows 2000 fron Java. I do this by
Process proc = Runtime.getRuntime().exec(cmd);
cmd is a String representing a command. For instance I try to control the gnupg program by
"cmd /c C:\\gnupg\\gpg --list-keys"
This works fine. But when I want to make a more advanced control, when gnupg waits for more than one input, and that input can't be put on the same line I get problems.
When running gpg --edit-key SomeKey on the command line I have to enter
trust - return - 5 - return - yes - return - quit
How do I do this?

Answer 1

this is how to do it! gotta listen to the output to prevent deadlock. you can pass in parameters o the initial call as well (a string array, where string[0] = command, string[...] = input argument) or write it to the output stream of the process.
hope this helps
public void run_command(String starting_command, String[] further_commands)
Process proc = Runtime.getRuntime().exec(starting_command);
Listener.make(proc.getInputStream());//these listen to the streams
Listener.make(proc.getErrorStream());//which prevents deadlock
PrintWriter writer = new PrintWriter(new OutputStreamWriter(proc.getOutputStream()));
for(int i = 0;i < further_commands.length;i++)
writer.println(further_commands);//you could put the extra stuff as the first string in this array
import java.io.*;
public class Listener extends Runnable
BufferedReader reader;
public static void make(InputStream in)
Listener l = new Listener(in);
Thread thread = new Thread(l);
thread.start();
public Listener(InputStream in)
reader = new BufferedReader(new InputStreamReader(in));
public void run()
String string;
while(true)
string = reader.readLine();
try
Thread.sleep(1000);
catch(Exception e)