Starting a process in Java?

Question

Is there a way to start a process in Java? in .Net this is done with for example:

system.diagnostics.process.start("processname");

Is there an equivalent in Java so I can then let the user find the application and then it would work for any OS.

Thanks

How does that work if I provide a file?

Answer 1

See Runtime.exec() and the Process class. In its simplest form:

Process myProcess = Runtime.getRuntime().exec(command);
...

Note that you also need to read the process' output (eg: myProcess.getInputStream()) -- or the process will hang on some systems. This can be highly confusing the first time, and should be included in any introduction to these APIs. See James P.'s response for an example.

You might also want to look into the new ProcessBuilder class, which makes it easier to change environment variables and to invoke subprocesses :

Process myProcess = new ProcessBuilder(command, arg).start();
...

Answer 2

http://www.rgagnon.com/javadetails/java-0014.html

import java.io.*;
public class CmdExec {

  public static void main(String argv[]) {
    try {
      String line;
      Process p = Runtime.getRuntime().exec
        (System.getenv("windir") +"\\system32\\"+"tree.com /A");
      BufferedReader input =
        new BufferedReader
          (new InputStreamReader(p.getInputStream()));
      while ((line = input.readLine()) != null) {
        System.out.println(line);
      }
      input.close();
    }
    catch (Exception err) {
      err.printStackTrace();
    }
  }
}

You can get the local path using System properties or a similar approach.

http://download.oracle.com/javase/tutorial/essential/environment/sysprop.html