Pass Context from Activity

Question

Ok straight to the point I'm a beginner in this android programming, I have question about How to pass context from my activity due to "cant resolve method getapplicationcontext"

this is MyLocationListener.java :

 public class MyLocationListener implements LocationListener {
        // Dipanggil saat ada perubahan lokasi geografis pengguna

private Context mContext;

    public MyLocationListener(Context context) {
        mContext = context;
    }

        @Override
        public void onLocationChanged(Location location) {
    // Mendapatkan nilai latitude dari lokasi terbaru
            double latitude = location.getLatitude();

    // Mendapatkan nilai longitude dari lokasi terbaru
            double longitude = location.getLongitude();

    // Menampilkan lokasi terbaru menggunakan Toast
            String message = "Lokasi saat ini :\n" +
                    "Latitude  = " + latitude + "\n" +
                    "Longitude = " + longitude;
            Toast.makeText(getApplicationContext(),
                    message, Toast.LENGTH_LONG).show();
        }

        // Dipanggil saat provider dinon-aktifkan oleh pengguna
        @Override
        public void onProviderDisabled(String provider) {
            String message = "GPS disabled";
            Toast.makeText(getApplicationContext(),
                    message, Toast.LENGTH_LONG).show();
        }

        // dipanggil saat provider diaktifkan oleh pengguna
        @Override
        public void onProviderEnabled(String provider) {
            String message = "GPS enabled";
            Toast.makeText(getApplicationContext(),
                    message, Toast.LENGTH_LONG).show();
        }

        // dipanggil saat ada perubahan status pada provider
        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub
        }
    }

This is my activity (GPSSample.java) :

public class GPSSample extends Activity {
        /** Called when the activity is first created. */
        @Override

LocationListener myLocationListener = new MyLocationListener(this);

        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

    // Inisiasi LocationManager dan LocationListener
            LocationManager myLocationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
            LocationListener myLocationListener = new MyLocationListener();
            myLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, myLocationListener);
        }

It said that I should use constructor to pass it, but how? I have Some constructor sample but I have no idea where to put it, and rename it based on my script

MyClass myClass = new MyClass(this);

Then create a constructor in that class that accepts Context as a param and use that

public class MyClass  
{ 
    Context c;
    public MyClass(Context context)
    { 
         c= context;
     } 
}} 

Thanks for the help...

Answer 1

1

You need to pass context as incoming parameter.

public class MyLocationListener implements LocationListener {

    // Dipanggil saat ada perubahan lokasi geografis pengguna
    private Context mContext;

    public MyLocationListener(Context context) {
        mContext = context;
    }

    @Override
    public void onLocationChanged(Location location) {
// Mendapatkan nilai latitude dari lokasi terbaru
        double latitude = location.getLatitude();

// Mendapatkan nilai longitude dari lokasi terbaru
        double longitude = location.getLongitude();

// Menampilkan lokasi terbaru menggunakan Toast
        String message = "Lokasi saat ini :\n" +
                "Latitude  = " + latitude + "\n" +
                "Longitude = " + longitude;
        // change getApplicationContext() to mContext(inner context reference)
        Toast.makeText(mContext,
                message, Toast.LENGTH_LONG).show();
    }

    // Dipanggil saat provider dinon-aktifkan oleh pengguna
    @Override
    public void onProviderDisabled(String provider) {
        String message = "GPS disabled";
        // change getApplicationContext() to mContext(inner context reference)
        Toast.makeText(mContext,
                message, Toast.LENGTH_LONG).show();
    }

    // dipanggil saat provider diaktifkan oleh pengguna
    @Override
    public void onProviderEnabled(String provider) {
        String message = "GPS enabled";
        // change getApplicationContext() to mContext(inner context reference)
        Toast.makeText(mContext,
                message, Toast.LENGTH_LONG).show();
    }

    // dipanggil saat ada perubahan status pada provider
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
    }
}

And set it in Activity :

LocationListener myLocationListener = new MyLocationListener(this);

2

Also you can use self-reference using .this construction. .this - in Java - is a reference for himself. But if class is static - you getting compile error.

Answer 2

Just use GPSSample.this instead of getApplicationContext(). This is the "outer this" i.e. the this of the parent class that, in this case, is the activity (and an activity is a subclass of a context).

If you will need to move the listener (I don't think so), use the constructor. Usually you will even use anonymous classes instead of concrete one for listeners. It's more direct and clear to read.