package com.example.ronaldbenjamin.mapdirection;
import android.Manifest; import android.annotation.SuppressLint;
import android.content.pm.PackageManager; import
android.graphics.Color; import android.os.AsyncTask; import
android.support.annotation.NonNull; import
android.support.v4.app.ActivityCompat; import
android.support.v4.app.FragmentActivity; import android.os.Bundle;
import android.widget.Toast;
import com.google.android.gms.maps.CameraUpdateFactory; import
com.google.android.gms.maps.GoogleMap; import
com.google.android.gms.maps.OnMapReadyCallback; import
com.google.android.gms.maps.SupportMapFragment; import
com.google.android.gms.maps.model.BitmapDescriptor; import
com.google.android.gms.maps.model.BitmapDescriptorFactory; import
com.google.android.gms.maps.model.LatLng; import
com.google.android.gms.maps.model.MarkerOptions; import
com.google.android.gms.maps.model.PolylineOptions;
import org.json.JSONException; import org.json.JSONObject;
import java.io.BufferedReader; import java.io.IOException; import
java.io.InputStream; import java.io.InputStreamReader; import
java.net.HttpRetryException; import java.net.HttpURLConnection;
import java.net.MalformedURLException; import java.net.URL; import
java.util.ArrayList; import java.util.HashMap; import
java.util.List;
public class MapsActivity extends FragmentActivity implements
OnMapReadyCallback {
private GoogleMap mMap;
private static final int LOCATION_REQUEST=500;
ArrayList<LatLng> listPoints;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// 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);
listPoints=new ArrayList<>();
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.getUiSettings().setZoomControlsEnabled(true);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) !=
PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_COARSE_LOCATION) !=
PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.ACCESS_FINE_LOCATION},LOCATION_REQUEST);
return;
}
mMap.setMyLocationEnabled(true);
mMap.setOnMapLongClickListener(new GoogleMap.OnMapLongClickListener() {
@Override
public void onMapLongClick(LatLng latLng) {
//reset marker when 2
if(listPoints.size()== 2){
listPoints.clear();
mMap.clear();
}
//save first point select
listPoints.add(latLng);
//create marker
MarkerOptions markerOptions=new MarkerOptions();
markerOptions.position(latLng);
if (listPoints.size()== 1){
//Add first marker to the map
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
}else{
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}
mMap.addMarker(markerOptions);
//TODO: reqest direction
if (listPoints.size()==2){
String url=getRequestUrl(listPoints.get(0),listPoints.get(1));
TaskRequestDirections taskRequestDirections=new TaskRequestDirections();
taskRequestDirections.execute(url);
}
}
});
}
private String getRequestUrl(LatLng origin, LatLng dest) {
//values of origin
String str_org="origin=" +origin.latitude+","+origin.longitude;
String str_dest="destination" + dest.latitude+","+dest.longitude;
String sensor="sensor-false";
String mode="mode-driving";
String param= str_org+"&"+str_dest+"&" +sensor+"&" +mode;
String output="json";
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();
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;
}
@SuppressLint("MissingPermission")
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode){
case LOCATION_REQUEST:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
mMap.setMyLocationEnabled(true);
}
break;
}
}
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 jason
TaskParser taskParser=new TaskParser();
taskParser.execute(s);
}
}
public class TaskParser extends AsyncTask<String,Void, List<List<HashMap<String, String>>>> //errror
{
@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 directionParser=new DirectionParser();
routes=directionParser.parse(jsonObject);
} catch (JSONException e) {
e.printStackTrace();
}
return routes;
}
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> lists) {
ArrayList points=null;
PolylineOptions polylineOptions=null;
for(List<HashMap<String, String>> path:lists)/// error {
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){
mMap.addPolyline(polylineOptions);
}
else
{
Toast.makeText(getApplicationContext(),"direction not found",Toast.LENGTH_SHORT).show();
}
}
} }
：致命的例外：主要 处理：com.example.ronaldbenjamin.mapdirection，PID：23351 java.lang.NullPointerException：尝试调用接口方法＆＃39; java.util.Iterator java.util.List.iterator（）＆＃39; 在...上 null对象引用 在输入代码herecom.example.ronaldbenjamin.mapdirection.MapsActivity $ TaskParser.onPostExecute（MapsActivity.java:239） strong 文本 at com.example.ronaldbenjamin.mapdirection.MapsActivity $ TaskParser.onPostExecute（MapsActivity.java:216)