Issue
One simple question: is it possible to return a value in AsyncTask
?
//AsyncTask is a member class
private class MyTask extends AsyncTask<Void, Void, Void>{
protected Void doInBackground(Void... params) {
//do stuff
return null;
}
@Override
protected void onPostExecute(Void result) {
//do stuff
//how to return a value to the calling method?
}
}
And then within my Activity
/Fragment
:
// The task is started from activity
myTask.execute()
// something like this?
myvalue = myTask.getvalue()
EDIT: This was asked a long time ago where I wasn't familiar with Java, now that I'm better with it, I 'll do a quick summary:
The point of async task is that the task is asynchronous
, meaning that after you call execute()
on the task, the task starts running on a thread of its own. returning a value from asynctask would be pointless because the original calling thread has already carried on doing other stuff (thus the task is asynchronous).
Think of time: At one point of time, you started a task that will run in parallel with the main thread. When the parallel-running task completed, time has also elapsed on the main thread. The parallel task cannot go back in time to return a value to the main thread.
I was coming from C so I didn't know much about this. But it seems that lots of people are having the same question so I thought I would clear it up a bit.
Solution
Why not call a method that handles the value?
public class MyClass extends Activity {
private class myTask extends AsyncTask<Void, Void, Void> {
//initiate vars
public myTask() {
super();
//my params here
}
protected Void doInBackground(Void... params) {
//do stuff
return null;
}
@Override
protected void onPostExecute(Void result) {
//do stuff
myMethod(myValue);
}
}
private myHandledValueType myMethod(Value myValue) {
//handle value
return myHandledValueType;
}
}
Answered By - ababzy
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