Synchronously executing long running methods in a Service

Question

I have an android service that has a set of operations :

MyService.java

public class MyService extends Service {

    public int login() {
      //Invokes yet another logic to initiate login and waits for result 
      //synchronously and returns status code based on result of operation
    }

    public int logout() {
      //Invokes yet another logic to initiate logout and waits for result 
      //synchronously and returns the status code
    }
}

I am invoking the methods from a client activity say, MyClientActivity.java residing in the same process.

For each operations the service invokes some logic and waits for the result in a synchronous manner. When the service is executing all of this logic I do not want the user to perform anything else and just show a loading screen. So basically, after I have initiated an operation I want MyClientActivity to wait for the status code synchronously. Now I know that I cannot block the UI thread to avoid ANR.
How can I make this operation execute on a separate thread and then get the result back so that I can appropriately propagate the result back to the user by changing the UI based on this result.

I am pretty new to this and can't really grasp the concepts. If someone can explain along with an example that would be helpful.

Answer 1

I accomplished this by using a HandlerThread to create a Handler to which I am posting Runnables to do the background tasks.
To do that main thread tasks (UI tasks) I am using mainLooper to create another Handler to which I posts Runnables to do operations on views.
A rough representation of the code :

mBackgroundHandler.post(new Runnable() {

    @Override
    public void run() {
        //Do background operation in synchronous manner as usual.

    mMainHandler.post(new Runnable() {
        @Override
        public void run() {
            //Remove loader, update UI
        }
    });
  }
});