Android async task to wait for other task to complete

Question

I have two asyc task both perform separate network operation.I want one async task to wait for other task to finish for a single variable..I thought of doing it like perform other asyc operation onPostexecute of first one but for a single variable i have to make other task to wait first one to finish...is there any to achieve efficently

Answer 1

Referring to this, you can not use .execute() so;

First you have to start your tasks like this:

// Start first task
new Task1().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, "");
// Start second task
new Task2().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, "");

and then you can make a static variable so the both of tasks can access to it:

public static boolean task1Finished = false;

Then simple example of the tasks:

First task

private class Task1 extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {
        Log.d("myApp", "Task1 started");

        for(int x = 0; x < 10; ++x)
        {
            try 
            {
                Thread.sleep(1000);
                //Log.d("myApp", "sleeped 1000 ms");
            } 
            catch (InterruptedException e) 
            {
                e.printStackTrace();
            }
        }
        return "";
    }

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected void onPostExecute(String result) {
        // Lets the second task to know that first has finished
        task1Finished = true;
    }
}

Second task

private class Task2 extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {
        Log.d("myApp", "Task2 started");
        while( task1Finished == false )
        {
            try 
            {
                Log.d("myApp", "Waiting for Task1");
                Thread.sleep(1000);
            } 
            catch (InterruptedException e) 
            {
                e.printStackTrace();
            }
        }

        Log.d("myApp", "Task1 finished");
        // Do what ever you like
        // ...
        return "";
    }

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected void onPostExecute(String result) {
        Log.d("myApp", "All done here (Task2)");
    }
}