I will suggest you to do is:

String[] str = {"D:","dir"};
Process proc = null;
ArrayList lines = new ArrayList();
BufferedReader in = null;
String s = null;
Runtime runtime = Runtime.getRuntime();
proc = runtime.exec(cmd);
in = new BufferedReader(new InputStreamReader(proc
               .getInputStream()));
while ( (s = in.readLine()) != null )
{
lines.add(s);
}

Tarun