Java obtains the PID used to start the application.

The following code obtains the private attributes of a class through java reflection! ProcessBuilder builder = new ProcessBuilder (); builder. directory (new File ("/opt/google/chrome"); // set the path of the Application builder. command ("chrome", "-- user-data-dir =/opt/temp"); // the startup command of the program try {final Process process = builder. start (); Timer timer = new Timer (); timer. schedule (new TimerTask () {@ Overridepublic void run () {try {Class clazz = Class. forName ("java. lang. UNIXProcess "); Field pidField = clazz. getDeclaredField ("pid"); pidField. setAccessible (true); Object value = pidField. get (process); System. err. println ("pid =" + value);} catch (Throwable e) {e. printStackTrace () ;}}, 2000) ;}catch (IOException e1) {e1.printStackTrace ();}