executing runOnUiThread on a separate class [duplicate]

Answer 1

You need to have the Activity's reference (lets name it activity) and pass it to your AsyncTask class. Then you can call runOnUiThread like this:

activity.runOnUiThread

The runOnUiThread is a method defined in Activity class.

Just add a contsructor to your AsyncTask. Your AsyncTask will look like this:

public class AdamTask extends AsyncTask<String, Void, String> {

private Activity activity; //activity is defined as a global variable in your AsyncTask

public AdamTask(Activity activity) {

    this.activity = activity;
}

public void showToast(final String toast)
    {
        activity.runOnUiThread(new Runnable() {
            public void run()
            {
                Toast.makeText(activity, toast, Toast.LENGTH_SHORT).show();
            }
        });
    }

...

}

Then to call the AsyncTask you need something like this:

AdamTask adamTask = new AdamTask(Eve.this);
adamTask.excecute(yourParams);

UPDATE As Sam mentioned in the comments, AsyncTasks may result in context leaking when configuration changes occur (one example is when screen rotates and the Activity is recreated). A way to deal with this is the headless fragment technique.

Another way, more efficient, is using an event bus. See here for more information (link provided by Sam in the comments).

Answer 2

Just typecast the context to Activity class

((Activity)context).runOnUiThread(new Runnable()
    {
        public void run()
        { 
             Toast.makeText(context, toast, Toast.LENGTH_SHORT).show();
        }
    });

Answer 3

You need your Activity object to do this. Pass your Activity's this reference through the constructor and use it in your AsyncTask.

public class AdamTask extends AsyncTask<String, Void, String>{
         public void showToast(final String toast)
        {
            activityObj.runOnUiThread(new Runnable() {
                public void run()
                {
                    Toast.makeText(context, toast, Toast.LENGTH_SHORT).show();
                }
            });
        }
}

Since runOnUiThread is a public method in Activity class, you cannot use it in some other Custom class or class that extends other than Activity itself.

Look here, runonUi.

If you are not clear, please check this answer to learn how to send Activity Object through constructor