私が開発したいAndroidアプリでは、ユーザーが自分の位置を見つけられるようにしたいと考えています。これを行うには、MainActivity にこのコードがありますが、デバイス上で (実行すると) 緯度経度と住所が見つかりません。なぜですか?
public class MainActivity extends Activity implements LocationListener {
private TextView latituteField;
private TextView longitudeField;
private TextView addressField; //Add a new TextView to your activity_main to display the address
private LocationManager locationManager;
private String provider;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
latituteField = (TextView) findViewById(R.id.TextView02);
longitudeField = (TextView) findViewById(R.id.TextView04);
addressField = (TextView) findViewById(R.id.TextView05); //Make sure you add this to activity_main
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
System.out.println("Provider " + provider + " has been selected.");
onLocationChanged(location);
} else {
latituteField.setText("Location not available");
longitudeField.setText("Location not available");
}
}
@Override
protected void onResume() {
super.onResume();
locationManager.requestLocationUpdates(provider, 400, 1, this);
}
@Override
protected void onPause() {
super.onPause();
locationManager.removeUpdates(this);
}
@Override
public void onLocationChanged(Location location) {
double lat = location.getLatitude();
double lng = location.getLongitude();
Geocoder geoCoder = new Geocoder(this, Locale.getDefault());
StringBuilder builder = new StringBuilder();
try {
List<Address> address = geoCoder.getFromLocation(lat, lng, 1);
int maxLines = address.get(0).getMaxAddressLineIndex();
for (int i=0; i<maxLines; i++) {
String addressStr = address.get(0).getAddressLine(i);
builder.append(addressStr);
builder.append(" ");
}
String fnialAddress = builder.toString(); //This is the complete address.
latituteField.setText(String.valueOf(lat));
longitudeField.setText(String.valueOf(lng));
addressField.setText(fnialAddress); //This will display the final address.
} catch (IOException e) {}
catch (NullPointerException e) {}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
Toast.makeText(this, "Enabled new provider " + provider,
Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(this, "Disabled provider " + provider,
Toast.LENGTH_SHORT).show();
}
}