Is it possible to end a process nicely in a Java application?

Question

In a Java application:

currentProcess = Runtime.getRuntime().exec("MyWindowsApp.exe");
...
currentProcess.destroy();

Calling destroy simply kills the process and doesn't allow any user cleanup or exit code to run. Is it possible to send a process a WM_CLOSE message or similar?

Answer 1

You could use Process.getOutputStream to send a message to the stdin of your app, eg:

PrintStream ps = new PrintStream(currentProcess.getOutputStream());
ps.println("please_shutdown");
ps.close();

Of course this means you have to contrive to listen on stdin in the Windows app.

Answer 2

you can try with JNA, importing user32.dll and defining an interface that defines at least CloseWindow

Answer 3

A dirty solution would be making your MyWindowsApp register its identifier somewhere like file and create another windows app that sends WM_CLOSE (let's name it MyWindowsAppCloser) to another applications.

With this in hand, you would code the following using java 1.6

currentProcess = Runtime.getRuntime().exec("MyWindowsApp.exe");
...

// get idMyWindowsApp where MyWindowsApp stored its identifier
killerProcess = new ProcessBuilder("MyWindowsAppCloser.exe", idMyWindowsApp).start();
killerProcess.waitFor();

int status = currentProcess.waitFor();

Answer 4

Not without resorting to native code. Process.destroy() causes a forced termination. On Windows this is equivalent to calling TerminateProcess(). On Unix it is equivalent to a SIGQUIT and causes the application to core dump.