I'm having a problem with my code. Displays the message: java.lang.NullPointerException: Attempt to invoke the interface method 'int java.util.List.size ()' on a null object reference. My code is:` public class MainActivity extends FragmentActivity implements GoogleMap.OnMyLocationButtonClickListener, OnMyLocationClickListener, OnMapReadyCallback {
private GoogleMap maps;
ArrayList<LatLng> markerPoints=new ArrayList<>();
MarkerOptions markerOptions;
MarkerOptions markerOpt;
LatLng latLng;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//parapobh sto SupportMapFragment ths Activity_main
SupportMapFragment fm = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map));
/* lhpsh xarth gia to SupportMapFragment */
fm.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
maps = googleMap;
LatLng Greece = new LatLng(37.97, 23.73);
//googleMap.addMarker(new MarkerOptions().position(Greece).title("Marker in Greece"));
//googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(Greece,16));
Button btn_find = (Button) findViewById(R.id.btn_find);
OnClickListener findClickListener = new OnClickListener() {
@Override
public void onClick(View v) {
EditText etLocation = (EditText) findViewById(R.id.et_location);
String location = etLocation.getText().toString();
if (location != null && !location.equals("")) {
new GeocoderTask().execute(location);
}
}
};
btn_find.setOnClickListener(findClickListener);
Button btn_go=(Button) findViewById(R.id.btn_go);
OnClickListener goClickListener=new OnClickListener() {
@Override
public void onClick(View v) {
EditText etDieuthinsh=(EditText) findViewById(R.id.et_dieuthinsh);
String dieuthinsh=etDieuthinsh.getText().toString();
if(dieuthinsh!=null && !dieuthinsh.equals("")){
new GeocoderTask1().execute(dieuthinsh);
}
}
};
btn_go.setOnClickListener(goClickListener);
}
private class GeocoderTask extends AsyncTask<String,Void,List<Address>> {
@Override
protected List<Address> doInBackground(String... locationName) {
Geocoder geocoder = new Geocoder(getBaseContext());
List<Address>addresses=null;
try {
addresses = geocoder.getFromLocationName(locationName[0], 8);
} catch (IOException e) {
e.printStackTrace();
}
return addresses;
}
@Override
protected void onPostExecute(List<Address>addresses) {
if (addresses==null||addresses.size()==0) {
Toast.makeText(getBaseContext(), "No Location found", Toast.LENGTH_SHORT).show();
}
maps.clear();
//try {
for (int t = 0; t < addresses.size(); t++) {
Address address = (Address) addresses.get(t);
latLng = new LatLng(address.getLatitude(), address.getLongitude());
String addressText = String.format("%s,%s", address.getMaxAddressLineIndex() > 0 ? address.getAddressLine(0) : "", address.getCountryName());
markerOptions = new MarkerOptions();
markerOptions.position(latLng);
/**
* for the start location,the color of marker is Green and*
* for the end location, the color of marker is Red
*/
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
//prosthesh neou deikth sto GoogleMaps Android API V2
markerOptions.title(addressText);
maps.addMarker(markerOptions);
if (t == 0)
maps.animateCamera(CameraUpdateFactory.newLatLng(latLng));
if (markerPoints.size() == 1) {
//lhpsh URL sto Google Directions API
String url = getDirectionsUrls(markerPoints.get(0));
DownloadTask downloadTask = new DownloadTask();
//xekinhste thn lhpsh dedomenwn json apo to Google Directions API
downloadTask.execute(url);
}
}
//} catch(NullPointerException e){
// e.printStackTrace();
// }
}
}
private class GeocoderTask1 extends AsyncTask<String, Void, List<Address>> {
@Override
protected List<Address> doInBackground(String... dieuthinshName) {
Geocoder geocoders = new Geocoder(getBaseContext());
List<Address> dieuts = null;
try {
dieuts = geocoders.getFromLocationName(dieuthinshName[0], 8);
} catch (IOException e) {
e.printStackTrace();
}
return dieuts;
}
@Override
protected void onPostExecute(List<Address> dieuts) {
if (dieuts == null || dieuts.size() == 0) {
Toast.makeText(getBaseContext(), "No Dieuthinsh found", Toast.LENGTH_SHORT).show();
}
maps.clear();
//try{
for (int k = 0; k < dieuts.size(); k++) {
Address address1 = (Address) dieuts.get(k);
latLng = new LatLng(address1.getLatitude(), address1.getLongitude());
String address1Text = String.format("%s,%s", address1.getMaxAddressLineIndex() > 0 ? address1.getAddressLine(0) : "", address1.getCountryName());
markerOpt = new MarkerOptions();
markerOpt.position(latLng);
markerOpt.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
markerOpt.title(address1Text);
maps.addMarker(markerOpt);
if (k == 0)
maps.animateCamera(CameraUpdateFactory.newLatLng(latLng));
if(markerPoints.size()==2) {
//lhpsh URL sto Google Directions API
String url1 = getDirectionsUrl(markerPoints.get(1));
DownloadTask1 downloadTask1 = new DownloadTask1();
//xekinhste thn lhpsh dedomenwn json apo to Google Directions API
downloadTask1.execute(url1);
}
}
// } catch (NullPointerException e) {
// e.printStackTrace();
//}
}
}
the answers that exist on the site do not solve the problem.
