findViewById in non-Activity class

Question

Still being relatively new to this I'm having issues in finding a view in a non-activity class MyLocation which I'm using in my activity class MainActivity. I'm using MyLocation to get longitude and latitude. I want to highlight a textview when either GPS or Network has been used. To do so I need to find the textviews in the non-activity class MyLocation.

Here is how I'm calling it in MainActivity:

public class MainActivity extends ActionBarActivity implements LocationListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

            MyLocation myLocation = new MyLocation();
            myLocation.getLocation(this, locationResult);

}

And here what I tried in MyLocation to find the textviews:

public class MyLocation {

LocationManager lm;
LocationResult locationResult;
private Context context;
TextView tvnetwork, tvgps;
private int defaultTextColor;

LocationListener locationListenerNetwork = new LocationListener() {
    public void onLocationChanged(Location location) {

        locationResult.gotLocation(location);

        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View v = inflater.inflate(R.layout.main, null);

        tvnetwork = (TextView) v.findViewById(R.id.tvnetwork);
        tvgps = (TextView) v.findViewById(R.id.tvgps);
        defaultTextColor = tvgps.getTextColors().getDefaultColor();

        tvnetwork.setTextColor(context.getResources().getColor(
                R.color.green));
        tvgps.setTextColor(defaultTextColor);

        lm.removeUpdates(this);
        lm.removeUpdates(locationListenerGps);
    }

    public void onProviderDisabled(String provider) {
    }

    public void onProviderEnabled(String provider) {
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
    }
};

But the views are not found. I already get a NPE @ .getSystemService(Context.LAYOUT_INFLATER_SERVICE);. What am I doing wrong?

Answer 1

get a NPE @ .getSystemService(Context.LAYOUT_INFLATER_SERVICE);. What am I doing wrong?

Because context is null in MyLocation class. use MyLocation class constructor to pass MainActivity context in MyLocation to access system services as:

Activity activity;
public MyLocation(Context context,Activity activity){
this.context=context;
this.activity=activity;
}

and in MainActivity create MyLocation class object by passing MainActivity context as:

MyLocation myLocation = new MyLocation(MainActivity.this,this);

Now use context to access system services in MyLocation class

EDIT: Instead of inflating main layout again in onLocationChanged use Activity context to access view from Activity Layout as:

 public void onLocationChanged(Location location) {

       ....
        tvnetwork = (TextView) activity.findViewById(R.id.tvnetwork);
        tvgps = (TextView) activity.findViewById(R.id.tvgps);
        defaultTextColor = tvgps.getTextColors().getDefaultColor();

        tvnetwork.setTextColor(context.getResources().getColor(
                R.color.green));
        tvgps.setTextColor(defaultTextColor);

       ....
    }

Answer 2

Try this way,hope this will help you to solve your problem.

public class MainActivity extends ActionBarActivity implements LocationListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        MyLocation myLocation = new MyLocation(this);
        myLocation.getLocation(this, locationResult);

    }
}

public class MyLocation {

    LocationManager lm;
    LocationResult locationResult;
    private Context context;
    TextView tvnetwork, tvgps;
    private int defaultTextColor;

    public void MyLocation(Context context) {
        this.context = context;
    }

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {

            locationResult.gotLocation(location);

            View v = LayoutInflater.from(context).inflate(R.layout.main, null);

            tvnetwork = (TextView) v.findViewById(R.id.tvnetwork);
            tvgps = (TextView) v.findViewById(R.id.tvgps);
            defaultTextColor = tvgps.getTextColors().getDefaultColor();

            tvnetwork.setTextColor(context.getResources().getColor(
                    R.color.green));
            tvgps.setTextColor(defaultTextColor);

            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);
        }

        public void onProviderDisabled(String provider) {
        }

        public void onProviderEnabled(String provider) {
        }

        public void onStatusChanged(String provider, int status, Bundle extras) {
        }
    };
}