Question: I have this so far:

```
public static void main(String[] args) {

    try {
        String line;
        Process p = Runtime.getRuntime().exec(
                System.getenv("windir") + "\\system32\\" + "tasklist.exe");

        BufferedReader input = new BufferedReader(new InputStreamReader(
                p.getInputStream()));

        while ((line = input.readLine()) != null) {
            System.out.println(line); // <-- Parse data here.
        }
        input.close();
    } catch (Exception err) {
        err.printStackTrace();
    }

    Scanner killer = new Scanner(System.in);

    int tokill;

    System.out.println("Enter PID to be killed: ");

    tokill = killer.nextInt();

}

```

}

I want to be able to kill a process based on the PID a user enters. How can I do this? (Only needs to work on Windows). \*NB: Must be able to kill any process, inc. SYSTEM processes, so I'm guessing a -F flag will be needed if using taskkill.exe to do this?

So if I had 

```
Runtime.getRuntime().exec("taskkill /F /PID 827");

```

how can I replace "827" with my tokill variable?

Answer: 
I don't sit in front of a Windows computer right now. But if `tasklist` works for you, you can use [ProcessBuilder](http://docs.oracle.com/javase/6/docs/api/java/lang/ProcessBuilder.html) in order to run the windows command [taskkill](http://technet.microsoft.com/en-us/library/cc725602%28WS.10%29.aspx). Call `taskkill` like this with a `ProcessBuilder` instance `cmd /c taskkill /pid %pid%` (replace %pid% with the actual pid). You don't need the absolute path to both executables because `c:/windows/system32` is in the path variable.

As Eric (in a comment to your question) pointed out there are many who had this answer before.
The JavaSysMon library does the trick and has the benefit of being multi-platform: <https://github.com/danielflower/javasysmon> *(fork of the original, this one has a handy maven artifact)*

```
private static final JavaSysMon SYS_MON = new JavaSysMon();

// There is no way to transform a [Process] instance to a PID in Java 8. 
// The sysmon library does let you iterate over the process table.
// Make the filter match some identifiable part of your process and it should be a good workaround
int pid = Arrays.stream(SYS_MON.processTable())
    .filter(p -> p.getName().contains("python"))
    .findFirst().get().getPid()

// Kill the process
SYS_MON.killProcess(pid);
// Kill the process and its children, or only the children
SYS_MON.killProcessTree(pid, descendentsOnly);

```