Question

I am making a application that uses the GPS receiver. The application will work on all versions starting from 1.6. I have a satellite Icon in which I tell the users the current status:

• if icon is red – gps disabled
• if icon is orange – gps is enabled and trying to fix on the satellites
• if icon is green – gps is fixed and running fine.

After reading around here, I’ve found that some events for onLocationChanged trigger on 1.6 version but not later, so taking the advice I implemented a GPS listener. I have some really weird behavior as the status of the icon gets messed out. For instance I enable GPS and gets orange… after a fix get’s green.. after a few seconds gets read after a second orange and so on…

Here is the code I use. Please suggest what to change

public class TrackExecutionActivity extends Activity{

protected static final long GPS_UPDATE_TIME_INTERVAL=3000;  //millis
protected static final float GPS_UPDATE_DISTANCE_INTERVAL=0; //meters
private LocationManager mlocManager;
private MyGPSListener mGpsListener;
private LocationListener mlocListener; 

@Override
public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.trackexecution);

        imgGpsState = (ImageView)findViewById(R.id.imgGpsState);
        mlocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
        mlocListener = new MyLocationListener();
        mGpsListener = new MyGPSListener();
}

private class MyGPSListener implements GpsStatus.Listener {
        public void onGpsStatusChanged(int event) {
            boolean isGPSFix = false;
            switch (event) {
                case GpsStatus.GPS_EVENT_SATELLITE_STATUS:
                    if (mLastLocation != null)
                        isGPSFix = (SystemClock.elapsedRealtime() - mLastLocationMillis) < GPS_UPDATE_TIME_INTERVAL * 2;

                    if (isGPSFix) { // A fix has been acquired.
                        imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_green));
                    } else { // The fix has been lost.
                        imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_orange));
                    }

                    break;

                case GpsStatus.GPS_EVENT_FIRST_FIX:
                    imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_green));
                    break;
                case GpsStatus.GPS_EVENT_STARTED:
                    imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_orange));
                    break;
                case GpsStatus.GPS_EVENT_STOPPED:
                    imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_red));
                    break;
            }
        }
    }

public class MyLocationListener implements LocationListener
    {
        public void onLocationChanged(Location location)
        {
            if (location != null) {
                       mLastLocationMillis = SystemClock.elapsedRealtime();
            // do some things here
                     mLastLocation = location;

        }
        public void onProviderDisabled(String provider) 
        { 
            imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_red));
        } 

        public void onProviderEnabled(String provider) 
        { 
            imgGpsState.setImageDrawable(ctx.getResources().getDrawable(R.drawable.gps_on_orange));
        } 

        //this doesn't trigger on Android 2.x users say
        public void onStatusChanged(String provider, int status, Bundle extras) 
        { 
        }
        }
        }

 @Override
    protected void onResume() {
     if(mlocManager != null) {
         if (mGpsListener == null)
         {
            mGpsListener = new MyGPSListener();
         }

         if (mlocListener == null)
         {
            mlocListener = new MyLocationListener();
         }

        mlocManager.addGpsStatusListener(mGpsListener);
        mlocManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, GPS_UPDATE_TIME_INTERVAL, GPS_UPDATE_DISTANCE_INTERVAL, mlocListener);
      }
       super.onResume();
    }
}

Answer 1

change this:

isGPSFix = (SystemClock.elapsedRealtime() - mLastLocationMillis) < GPS_UPDATE_TIME_INTERVAL * 2;

your are setting a boolean with non boolean values.. hence the weird icon behavior during gps fixes you need to set that isGPSfix boolean somewhere.. for case of hasGPSfix or doesnothaveGPSfix..

You might have meant:

if ((SystemClock.elapsedRealtime() - mLastLocationMillis) < GPS_UPDATE_TIME_INTERVAL * 2) {
    isGPSFIX = true;
}