Killing a process using Java

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I would like to know how to "kill" a process that has started up. I am aware of the Process API, but I am not sure, If I can use that to "kill" an already running process, such as firefox.exe etc. If the Process API can be used, can you please point me into the correct direction? If not, what are the other available options? Thanks.

8 Answers

With Java 9, we can use ProcessHandle which makes it easier to identify and control native processes:

ProcessHandle
  .allProcesses()
  .filter(p -> p.info().commandLine().map(c -> c.contains("firefox")).orElse(false))
  .findFirst()
  .ifPresent(ProcessHandle::destroy)

where "firefox" is the process to kill.

This:

  • First lists all processes running on the system as a Stream<ProcessHandle>

  • Lazily filters this stream to only keep processes whose launched command line contains "firefox". Both commandLine or command can be used depending on how we want to retrieve the process.

  • Finds the first filtered process meeting the filtering condition.

  • And if at least one process' command line contained "firefox", then kills it using destroy.

No import necessary as ProcessHandle is part of java.lang.

You can kill a (SIGTERM) a windows process that was started from Java by calling the destroy method on the Process object. You can also kill any child Processes (since Java 9).

The following code starts a batch file, waits for ten seconds then kills all sub-processes and finally kills the batch process itself.

ProcessBuilder pb = new ProcessBuilder("cmd /c my_script.bat"));
Process p = pb.start();
p.waitFor(10, TimeUnit.SECONDS);

p.descendants().forEach(ph -> {
    ph.destroy();
});

p.destroy();
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