Question

I am trying to execute external jar from java app.

What is the most elegant way to check if the process has been started successfully and running?

ExtApp.jar is long-term running process, so I can not use Process.waiFor() because it would block my app. I have come up with following code, with idea behind is that the exitValue() throws IllegalThreadStateException if the process has not been yet terminated.

boolean success = false;
try {
    Process process = Runtime.getRuntime().exec("java -jar ExtApp.jar");
    try {
        if (process.exitValue() == 0) 
            success = true;
    } catch (IllegalThreadStateException e) {
        success = true;
    }
} catch (Exception e) {}

System.out.println(success);

But it is kind of ugly solution. Any ideas for a better one?

Answer 1

There seems to be no elegant solution to the problem. E.g. I ran your code on my PC and got “success” though there is no ExtApp.jar on it. That is, from the point of view of Runtime.exec the process (java.exe) started successfully, no matter what happens afterwards.