Calling Looper more than once causes “sending message to a Handler on a dead thread”

Question

I am using an Executor [fixed thread pool] with my own ThreadFactory that adds a Looper:

Handler HANDLER = new Handler();
Executor    THREADS = Executors.newFixe         


        

Answer 1

If you check the source in android/os/MessageQueue.java, you can see something like the following

  if (mQuiting) {
                RuntimeException e = new RuntimeException(
                    msg.target + " sending message to a Handler on a dead thread");
                Log.w("MessageQueue", e.getMessage(), e);
                return false;
            } else if (msg.target == null) {
                mQuiting = true;
            }
   }

So the message queue is basically unusable after Looper.quit() has been called the first time, as it enqueues a Message with a null target, which is the magical identifier for the message queue to stop enqueuing and appear "dead".