How to open the command prompt and insert commands using Java?

Solution 1:

I know that people recommend staying away from rt.exec(String), but this works, and I don't know how to change it into the array version.

rt.exec("cmd.exe /c cd \""+new_dir+"\" & start cmd.exe /k \"java -flag -flag -cp terminal-based-program.jar\"");

Solution 2:

If you are running two commands at once just to change the directory the command prompt runs in, there is an overload for the Runtime.exec method that lets you specify the current working directory. Like,

Runtime rt = Runtime.getRuntime();
rt.exec("cmd.exe /c start command", null, new File(newDir));

This will open command prompt in the directory at newDir. I think your solution works as well, but this keeps your command string or array a little cleaner.

There is an overload for having the command as a string and having the command as a String array.

You may find it even easier, though, to use the ProcessBuilder, which has a directory method to set your current working directory.

Hope this helps.

Solution 3:

public static void main(String[] args) {
    try {
        String ss = null;
        Process p = Runtime.getRuntime().exec("cmd.exe /c start dir ");
        BufferedWriter writeer = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
        writeer.write("dir");
        writeer.flush();
        BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
        BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
        System.out.println("Here is the standard output of the command:\n");
        while ((ss = stdInput.readLine()) != null) {
            System.out.println(ss);
        }
        System.out.println("Here is the standard error of the command (if any):\n");
        while ((ss = stdError.readLine()) != null) {
            System.out.println(ss);
        }

    } catch (IOException e) {
        System.out.println("FROM CATCH" + e.toString());
    }

}

Solution 4:

The following works for me on Snow Leopard:

Runtime rt = Runtime.getRuntime();
String[] testArgs = {"touch", "TEST"};
rt.exec(testArgs);

Thing is, if you want to read the output of that command, you need to read the input stream of the process. For instance,

Process pr = rt.exec(arguments);
BufferedReader r = new BufferedReader(new InputStreamReader(pr.getInputStream()));

Allows you to read the line-by-line output of the command pretty easily.

The problem might also be that MS-DOS does not interpret your order of arguments to mean "start a new command prompt". Your array should probably be:

{"start", "cmd.exe", "\c"}

To open commands in the new command prompt, you'd have to use the Process reference. But I'm not sure why you'd want to do that when you can just use exec, as the person before me commented.