Passing events from a non-activity class to an Activity class

Question

I have an activity class A for the layout and a non-activity class B for Location Request; the class B triggers some events like onConnectionSuspended and i want to get these back in the classe A. How can i do that ?
Thank you for the previous answers, i worked on it but i add some details.

I want to separate the Activity code from the GoogleApi.Connection code. To do that i made a non-activity class (maybe a service is better ?) with Connection code (see the structure code below).

1) Is it a good idea ?
2) If it is not, what is better to do (maybe put all in the same Activity ?) ?
3) If it is yes, i don't think that i can put some "Toast" in the connections events of my non-activity code so how can i get back the connections events in the Activity to display some messages ?
Thank you for the answers

import android.os.Bundle;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;

public class SATlocation implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener{

    @Override
    public void onConnected(Bundle bundle) {

    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }
}

Answer 1

use Local broadcast receiver add receiver in your activity as below

private BroadcastReceiver onNotice = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        // intent can contain anydata


    }

}

inside onresume register receiver as below

protected void onResume() {
    super.onResume();

    IntentFilter intentFilter = new IntentFilter(MyIntentService.ACTION);
    LocalBroadcastManager.getInstance(this).registerReceiver(onNotice, intentFilter);
}

unRegister receiver in onPause

protected void onPause() {
    super.onPause();
    LocalBroadcastManager.getInstance(this).unregisterReceiver(onNotice);
}

In your location service add following code to send local broadcast

Intent intent = new Intent("custom-event-name");
// You can also include some extra data.
intent.putExtra("message", "This is my message!");
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

Answer 2

As an alternative to broadcast receivers, if you have access to your class B instance from your Activity, you can also create an interface for listening to those events.

public interface LocationRequestEventListener {

    void onConnectionSuspended();
    ...

}

public class SomeActivity extends Activity implements LocationRequestEventListener {
    private ClassB classB;

    @Override
    public void onCreate() {
        ...
        classB.setListener(this);
    }

    ...

    @Override
    void onConnectionSuspended() {
        //react to the event here
    }

}

public class ClassB {
    private LocationRequestListener listener;

    ....

    public void setListener(LocationRequestListener listener) {
        this.listener = listener;
    }

    private void connectionSuspended() {
        // suppose this is where your class fire the event of interest
        if (listener != null) {
            listener.onConnectionSuspended();
        }
    }
}