Question

I want to use AsyncTask to call another application. I have a main app that does its own thing but when I launch it, it does an AsyncTask to call a “messages” application which checks to see if there are any unread messages and then displays a notification in the status bar.

However, when I called execute(), the messages application jumps to the front and I have to press the back button to get to my main application.

Code is as follows (my main application)

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    MessageUpdate update = new MessageUpdate(this);
    System.out.println("Calling Update");
    update.execute(null);
....

My AsyncTask:

public class MessageUpdate extends AsyncTask{

    Context ctx;
    public MessageUpdate(Context ctx){
        this.ctx = ctx;
    }

    @Override
    protected Object doInBackground(Object... params) {
        Intent notificationIntent = new Intent();
        notificationIntent.setClassName("com.test.messages", "com.test.messages.MessageCheck");
        ctx.startActivity(notificationIntent);
        return null;
    }
}

Can anyone tell my why the MessagesCheck jumps to the front and how to stop it? Or if what I’m doing is even feasible?

Answer 1

As others have pointed out, a service is the way to go. However, if you use bindService() the service will only last as long as it’s bound.

Just to clarify some of the issues:

• Using startActivity to communicate with a background task is not what you want, as an Activity is a user interface component, which will come to the front when activated.
• The suggestion is that you add a service to your “messages” application, not the main application.
• You can then communicate with the “messages” application from the main application by binding to the service. If you do this (using bindService), the service will not run indefinitely.
• The details of how to do this are here.

You could do all this without an AsyncTask, however it may help to avoid blocking the UI thread if the service takes significant time to do its job. Alternatively, your service could use a background thread of its own to check for messages and post the notification.