Execute Asynctask Several Times

Execute AsyncTask several times

AsyncTask instances can only be used one time.

Instead, just call your task like new MyAsyncTask().execute("");

From the AsyncTask API docs:

Threading rules

There are a few threading rules that must be followed for this class to work properly:

• The task instance must be created on the UI thread.
• execute(Params...) must be invoked on the UI thread.
• Do not call onPreExecute(), onPostExecute(Result), doInBackground(Params...), onProgressUpdate(Progress...) manually.
• The task can be executed only once (an exception will be thrown if a second execution is attempted.)

Android AsyncTask called multiple times

It literally means, that while AsyncTask is running, you cannot launch it again.
In your MainActivity.class you have line:

task.execute(); 

if task either is finished or not and you call the method again then exception will be thrown.

And put this method in onResume() is a good practice.
Only one thing to notice is: if you put in onRestart() remember, this callback works when you change configuration, but it will not be called if you Create activity.

The doc about lifecycle of an Activity.

execute asynctask multiple times or parallel in a loop

Create individual instance of AsyncTask inside the for loop.

for(..){
    //
    new MyAsyncTask().execute(obj.getString("source"));
}

Running same Asynctask multiple times sequentially

You could use a field variable in the outer class:

private int count;
private void attemptConnect(){
    count = 0;

    new MyTask().execute("");
}

class MyTask extends AsyncTask<String, String, String> {
    @Override
    protected String doInBackground(String... params) {
        return null;
    }

    @Override
    protected void onPostExecute(String s) {
        count++;
        if(count < 5){
            new MyTask().execute("");
        }
    }
}

Or pass in a count to the AsyncTask constructor:

private void attemptConnect(){
    new MyTask(0).execute("");
}

class MyTask extends AsyncTask<String, String, String> {
    private int count;

    public MyTask(int count){
        this.count = count;
    }

    @Override
    protected String doInBackground(String... params) {
        return null;
    }

    @Override
    protected void onPostExecute(String s) {
        if(count < 4){
            new MyTask(++count).execute("");
        }
    }
}

AsyncTask and error when executed twice

No. You cannot execute the same async task twice. You are able to do it again after 30 secs because the async task completes processing and returns the result from doInBackground(). Hence you need to create an object every time or use a progress dialog to block the user from clicking on the button again. Show the progress dialog in onPreExecute() and dismiss in onPostExecute().

Prevent asynctask from being executed multiple times

There are two Ways to do this.

1: Show a Progress Dialog and block the user for further input.

2: Create you AsyncTask variable in class scope private. Then this will never run more than once.

Is it possible to run multiple AsyncTask in same time?

use executor as follows

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
    new Save_data().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, location);
} else {
    new Save_data().execute(location);
}

See this

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