I'm not getting any output and probably the machine hangs with the code [duplicate]

Answer 1

The /F flag for CMD is for file completion. Its probably safe to assume that you want the /C flag to carry out the command. Without the /C flag, the cmd.exe will run interactively, looking for input, and your program will block indefinitely on waitFor. Replace:

new ProcessBuilder("cmd.exe", "/f", "dir");

with

new ProcessBuilder("cmd.exe", "/c", "dir");