Start CMD by using ProcessBuilder

Question

I am trying to start the CMD application in windows by using the following code, but it doesn't work as expected. Several examples from different websites shows that "cmd" as an argument in the ProcessBuilder construct should work.

What do I have to do to make my Java app open the CMD application in windows?

 public class JavaTest
 {
     public static void main(String[] args) 
     {
         ProcessBuilder pb = new ProcessBuilder("cmd");

         try 
         {
             pb.start();
             System.out.println("cmd started");
         } 
         catch (IOException e) 
         {
             System.out.println(e.getMessage());
         }  
     }
 }

When I try to use a non-existing application it actually prints out an error, so that means it actually runs "CMD". But the CMD application doesn't pop up as expected?

Solution 1

You need to use the start command. Actually, even I don't see a new command prompt popping up, but you can check that a new cmd.exe is definitely started using your task manager.

ProcessBuilder pb = new ProcessBuilder("cmd.exe", "/C", "start");

Though, the same functionality can be achieved using Runtime.exec(), and this actually pops up a new command prompt.

Runtime.getRuntime().exec("cmd.exe /C start");

Solution 2

To use it with ProcessBuilder you must separate the commands like this:

final List<String> commands = new ArrayList<String>();                

commands.add("cmd.exe");
commands.add("/C");
commands.add("start");
ProcessBuilder pb = new ProcessBuilder(commands);
pb.start();

Comments

[Birdman]

The ProcessBuilder doesn't work as expected (Which I find very, very weird) - But the "exec()" method does the job. Thank you!

[quest-lion]

String[] cmd = new String[]{"cmd.exe", "/C", "start"}; ProcessBuilder pb = new ProcessBuilder(cmd); Process process = pb.start();

[john]

I don't know what /C mean?,it's not the path of C drive

[Kazekage Gaara]

@john please see this : stackoverflow.com/questions/515309/what-does-cmd-c-mean