这是我的Android活动代码
public class driver_maps extends FragmentActivity implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private GoogleMap mGoogleMap;
String latitude,longitude,lat,lng,cmp,ID;
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(GoogleServiceAvailable())
{
//Toast.makeText(this,"Perfect!!!",Toast.LENGTH_LONG).show();
setContentView(R.layout.activity_driver_maps);
Intent test=getIntent();
latitude=test.getStringExtra("lat");
longitude=test.getStringExtra("lng");
cmp=test.getStringExtra("company");
ID=test.getStringExtra("driverID");
Toast.makeText(this,"Click on the map to activate the route",Toast.LENGTH_LONG).show();
initMap();
}
else
{
setContentView(R.layout.error);
}
}
public boolean GoogleServiceAvailable()
{
GoogleApiAvailability api=GoogleApiAvailability.getInstance();
int isAvailable=api.isGooglePlayServicesAvailable(this);
if (isAvailable== ConnectionResult.SUCCESS)
{
return true;
}
else if (api.isUserResolvableError(isAvailable))
{
Dialog dialog=api.getErrorDialog(this,isAvailable,0);
dialog.show();
}
else
{
Toast.makeText(this,"Cant connect to play services",Toast.LENGTH_LONG).show();
}
return false;
}
private void initMap() {
MapFragment mapFragment= (MapFragment) getFragmentManager().findFragmentById(R.id.mapFragment);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mGoogleMap=googleMap;
goToLocation(Double.parseDouble(latitude), Double.parseDouble(longitude),15);
mGoogleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener(){
@Override
public void onMapClick(LatLng point)
{
mGoogleMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(lat), Double.parseDouble(lng))).title("Origin.").icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
mGoogleMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(latitude), Double.parseDouble(longitude))).title("Destination.").icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_CYAN)));
LatLng origin = new LatLng(Double.parseDouble(lat), Double.parseDouble(lng));
LatLng dest = new LatLng(Double.parseDouble(latitude), Double.parseDouble(longitude));
// Getting URL to the Google Directions API
String url = getUrl(origin, dest);
Log.d("onMapClick", url.toString());
FetchUrl FetchUrl = new FetchUrl();
// Start downloading json data from Google Directions API
FetchUrl.execute(url);
}
});
}
public void goToLocation(double lat, double lng, float zoom) {
LatLng ll=new LatLng(lat,lng);
CameraUpdate update=CameraUpdateFactory.newLatLngZoom(ll,zoom);
mGoogleMap.moveCamera(update);
//mGoogleMap.addMarker(new MarkerOptions().position(new LatLng(lat,lng)).title("Destination."));
}
private String getUrl(LatLng origin, LatLng dest) {
// Origin of route
String str_origin = "origin=" + origin.latitude + "," + origin.longitude;
// Destination of route
String str_dest = "destination=" + dest.latitude + "," + dest.longitude;
// Sensor enabled
String sensor = "sensor=false";
// Building the parameters to the web service
String parameters = str_origin + "&" + str_dest + "&" + sensor;
// Output format
String output = "json";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;
return url;
}
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try {
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
Log.d("downloadUrl", data.toString());
br.close();
} catch (Exception e) {
Log.d("Exception", e.toString());
} finally {
iStream.close();
urlConnection.disconnect();
}
return data;
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
private class FetchUrl extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... url) {
// For storing data from web service
String data = "";
try {
// Fetching the data from web service
data = downloadUrl(url[0]);
Log.d("Background Task data", data.toString());
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
// Parsing the data in non-ui thread
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try {
jObject = new JSONObject(jsonData[0]);
Log.d("ParserTask", jsonData[0].toString());
DataParser parser = new DataParser();
Log.d("ParserTask", parser.toString());
// Starts parsing data
routes = parser.parse(jObject);
Log.d("ParserTask", "Executing routes");
Log.d("ParserTask", routes.toString());
} catch (Exception e) {
Log.d("ParserTask", e.toString());
e.printStackTrace();
}
return routes;
}
/////
// Executes in UI thread, after the parsing process
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points;
PolylineOptions lineOptions = null;
// Traversing through all the routes
for (int i = 0; i < result.size(); i++) {
points = new ArrayList<>();
lineOptions = new PolylineOptions();
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
// Fetching all the points in i-th route
for (int j = 0; j < path.size(); j++) {
HashMap<String, String> point = path.get(j);
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
// Adding all the points in the route to LineOptions
lineOptions.addAll(points);
lineOptions.width(10);
lineOptions.color(Color.RED);
Log.d("onPostExecute","onPostExecute lineoptions decoded");
}
// Drawing polyline in the Google Map for the i-th route
if(lineOptions != null) {
mGoogleMap.addPolyline(lineOptions);
}
else {
Log.d("onPostExecute","without Polylines drawn");
}
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
@Override
public void onLocationChanged(Location location) {
Toast.makeText(getApplicationContext(), "TEST TO SEE IF WORKING", Toast.LENGTH_LONG).show();
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
//Place current location marker
lat=String.valueOf(location.getLatitude());
lng=String.valueOf(location.getLongitude());
Toast.makeText(getApplicationContext(), "Latitude "+lat+" Longitude "+lng, Toast.LENGTH_LONG).show();
Response.Listener<String> responseListener = new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject jsonResponse = new JSONObject(response);
boolean success = jsonResponse.getBoolean("success");
if (success) {
Toast.makeText(getApplicationContext(), "Location changed...", Toast.LENGTH_LONG).show();
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(driver_maps.this);
builder.setMessage("Updating Location Failed")
.setNegativeButton("Retry", null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
UpdateLocation updateLocation=new UpdateLocation(cmp,ID,Double.parseDouble(lat), Double.parseDouble(lng),responseListener);
RequestQueue queue = Volley.newRequestQueue(driver_maps.this);
queue.add(updateLocation);
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mGoogleMap.addMarker(markerOptions);
//move map camera
mGoogleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mGoogleMap.animateCamera(CameraUpdateFactory.zoomTo(11));
//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
@Override
public void onConnected(@Nullable Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
android.Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
@Override
public void onConnectionSuspended(int i) {
}
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
public boolean checkLocationPermission(){
if (ContextCompat.checkSelfPermission(this,
android.Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Asking user if explanation is needed
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
android.Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(this,
new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
return false;
} else {
return true;
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted. Do the
// contacts-related task you need to do.
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient == null) {
buildGoogleApiClient();
}
mGoogleMap.setMyLocationEnabled(true);
}
} else {
// Permission denied, Disable the functionality that depends on this permission.
Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();
}
return;
}
// other 'case' lines to check for other permissions this app might request.
// You can add here other case statements according to your requirement.
}
}
}
它在我添加原点标记的行上给出了一个错误，我猜测它是因为lat / lng值为null，因为onlocationchanged没有工作 这是运行时的堆栈跟踪：
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.trim()' on a null object reference
at java.lang.StringToReal.parseDouble(StringToReal.java:263)
at java.lang.Double.parseDouble(Double.java:301)
at com.example.omara.trackit.driver_maps$1.onMapClick(driver_maps.java:118)