当我尝试在地图上放置从源到目的地的方向时 此空指针异常heppen 当我尝试在地图上将从源到目的地的方向 这个空指针异常会变
SELECT u.*
FROM users u
LEFT JOIN blocked b ON (u.id = b.idBlock AND b.idBlocked = 3)
WHERE u.id <> 3
AND b.id IS NULL;
ocat：
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map.class如下：
07-05 02:19:21.569 23133-23133/com.example.saad.testapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.saad.testapp, PID: 23133
java.lang.NullPointerException
at com.example.saad.testapp.map$TaskParser.onPostExecute(map.java:248)
at com.example.saad.testapp.map$TaskParser.onPostExecute(map.java:205)
at android.os.AsyncTask.finish(AsyncTask.java:632)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5511)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
下面一行有例外
public class map extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
loc ambLoc;
loc patLoc;
String tempE;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
ambLoc=new loc();
patLoc=new loc();
tempE=new String();
}
@Override
public void onMapReady(GoogleMap googleMap) {
getPoints();
}
void getPoints()
{
//some code here
String url=getRequestUrl(ambLoc,patLoc);
TaskRequestDirections taskRequestDirections = new TaskRequestDirections();
taskRequestDirections.execute(url);
}
private String getRequestUrl(loc origin, loc dest) {
//Value of origin
String str_org = "origin=" + origin.getLatitude() +","+origin.getLongitude();
//Value of destination
String str_dest = "destination=" + dest.getLatitude()+","+dest.getLongitude();
//Set value enable the sensor
String sensor = "sensor=false";
//Mode for find direction
String mode = "mode=driving";
//Build the full param
String param = str_org +"&" + str_dest + "&" +sensor+"&" +mode;
//Output format
String output = "json";
//Create url to request
String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + param;
return url;
}
private String requestDirection(String reqUrl) throws IOException {
String responseString = "";
InputStream inputStream = null;
HttpURLConnection httpURLConnection = null;
try{
URL url = new URL(reqUrl);
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.connect();
//Get the response result
inputStream = httpURLConnection.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
StringBuffer stringBuffer = new StringBuffer();
String line = "";
while ((line = bufferedReader.readLine()) != null) {
stringBuffer.append(line);
}
responseString = stringBuffer.toString();
bufferedReader.close();
inputStreamReader.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
inputStream.close();
}
httpURLConnection.disconnect();
}
return responseString;
}
public class TaskRequestDirections extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... strings) {
String responseString = "";
try {
responseString = requestDirection(strings[0]);
} catch (IOException e) {
e.printStackTrace();
}
return responseString;
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
//Parse json here
TaskParser taskParser = new TaskParser();
taskParser.execute(s);
}
}
在
上有例外
public class TaskParser extends AsyncTask<String, Void, List<List<HashMap<String, String>>> > {
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... strings) {
JSONObject jsonObject = null;
List<List<HashMap<String, String>>> routes = null;
try {
jsonObject = new JSONObject(strings[0]);
DirectionParser directionsParser = new DirectionParser();
routes = directionsParser.parse(jsonObject);
} catch (JSONException e) {
e.printStackTrace();
}
return routes;
}
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> lists) {
//Get list route and display it into the map
ArrayList points = null;
PolylineOptions polylineOptions = null;
for (List<HashMap<String, String>> path : lists) {
points = new ArrayList();
polylineOptions = new PolylineOptions();
for (HashMap<String, String> point : path) {
double lat = Double.parseDouble(point.get("lat"));
double lon = Double.parseDouble(point.get("lon"));
points.add(new LatLng(lat,lon));
}
polylineOptions.addAll(points);
polylineOptions.width(15);
polylineOptions.color(Color.BLUE);
polylineOptions.geodesic(true);
}
if (polylineOptions!=null) {
Toast.makeText(getApplicationContext(), "adding polyline!", Toast.LENGTH_SHORT).show();
建议任何解决方案（如果有） 谢谢 谢谢 谢谢 谢谢
答案 0 :(得分：1)
您永远不会设置mMap变量尝试
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
getPoints();
}