Question

I created an asynctask and in its doInBackground() method i started a thread like this:

private class myAsyntask extends Asynctask{

    doInBackground(){
    Thread t = new Thread(new Runnable(){
     public void run()
     {
        while(someBoolean!=true){
        Thread.currentThread.sleep(100);
        } 
     }
     });
    }
   onPostExecute(){
  //do something related to that variable
  }
}

problem I am facing is after 1st iteration of Thread.sleep() , onPostExecute() is called , instead I thought that asynctask will run this thread on background and when that boolean is true onPostexecute() is called.I am not able to understand why this happens ?

Answer 1

AsyncTask automatically creates a new Thread for you, so everything you do in doInBackground() is on another thread.
What you are doing is this:

1. AsyncTask creates a new Thread and runs doInBackground().
2. a new Thread (t) is created from the AsyncTask-Thread.
3. doInBackground() is completed, as all it does is create the Thread t and thus jumps to onPostExecute().
4. Thread t would still be running in the background (however, you do not call start() on t, meaning that it is not started).

Instead you want your doInBackground() method to look something like this:

doInBackground(){
    while(someBoolean!=true){
        //Perform some repeating action.
        Thread.sleep(100);
    } 
}