问题
This is the first time I have tried to do anything with play services and google maps/places API. I am getting a NPE error when trying to launch the activity.
06-10 09:15:45.704 19942-19942/com.rcd.mypr E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.rcd.mypr, PID: 19942
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rcd.mypr/com.rcd.mypr.BoxLocator.BoxLocator}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2269)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5102)
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:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.rcd.mypr.BoxLocator.BoxLocator.initCompo(BoxLocator.java:137)
at com.rcd.mypr.BoxLocator.BoxLocator.onCreate(BoxLocator.java:43)
at android.app.Activity.performCreate(Activity.java:5248)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2173)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2269)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5102)
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:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Here is my maps_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.MapFragment"/>
BoxLocator.java
package com.rcd.mypr.BoxLocator;
import android.app.ActionBar;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.ArrayAdapter;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.rcd.mypr.R;
import java.util.ArrayList;
public class BoxLocator extends Activity {
private final String TAG = getClass().getSimpleName();
private GoogleMap mMap;
private String[] places;
private LocationManager locationManager;
private Location loc;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initCompo();
places = getResources().getStringArray(R.array.places);
currentLocation();
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
actionBar.setListNavigationCallbacks(ArrayAdapter.createFromResource(
this, R.array.places, android.R.layout.simple_list_item_1),
new ActionBar.OnNavigationListener() {
@Override
public boolean onNavigationItemSelected(int itemPosition,
long itemId) {
Log.e(TAG,
places[itemPosition].toLowerCase().replace("-",
"_"));
if (loc != null) {
mMap.clear();
new GetPlaces(BoxLocator.this,
places[itemPosition].toLowerCase().replace(
"-", "_").replace(" ", "_")).execute();
}
return true;
}
});
}
private class GetPlaces extends AsyncTask<Void, Void, ArrayList<Place>> {
private ProgressDialog dialog;
private Context context;
private String places;
public GetPlaces(Context context, String places) {
this.context = context;
this.places = places;
}
@Override
protected void onPostExecute(ArrayList<Place> result) {
super.onPostExecute(result);
if (dialog.isShowing()) {
dialog.dismiss();
}
for (int i = 0; i < result.size(); i++) {
mMap.addMarker(new MarkerOptions()
.title(result.get(i).getName())
.position(
new LatLng(result.get(i).getLatitude(), result
.get(i).getLongitude()))
.icon(BitmapDescriptorFactory
.fromResource(R.drawable.pin))
.snippet(result.get(i).getVicinity()));
}
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(new LatLng(result.get(0).getLatitude(), result
.get(0).getLongitude())) // Sets the center of the map to
// Mountain View
.zoom(14) // Sets the zoom
.tilt(30) // Sets the tilt of the camera to 30 degrees
.build(); // Creates a CameraPosition from the builder
mMap.animateCamera(CameraUpdateFactory
.newCameraPosition(cameraPosition));
}
@Override
protected void onPreExecute() {
super.onPreExecute();
dialog = new ProgressDialog(context);
dialog.setCancelable(false);
dialog.setMessage("Loading..");
dialog.isIndeterminate();
dialog.show();
}
@Override
protected ArrayList<Place> doInBackground(Void... arg0) {
PlacesService service = new PlacesService(
"Put your project browser API key here");
ArrayList<Place> findPlaces = service.findPlaces(loc.getLatitude(), // 28.632808
loc.getLongitude(), places); // 77.218276
for (int i = 0; i < findPlaces.size(); i++) {
Place placeDetail = findPlaces.get(i);
Log.e(TAG, "places : " + placeDetail.getName());
}
return findPlaces;
}
}
private void initCompo() {
mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
.getMap();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private void currentLocation() {
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
String provider = locationManager
.getBestProvider(new Criteria(), false);
Location location = locationManager.getLastKnownLocation(provider);
if (location == null) {
locationManager.requestLocationUpdates(provider, 0, 0, listener);
} else {
loc = location;
new GetPlaces(BoxLocator.this, places[0].toLowerCase().replace(
"-", "_")).execute();
Log.e(TAG, "location : " + location);
}
}
private LocationListener listener = new LocationListener() {
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onLocationChanged(Location location) {
Log.e(TAG, "location update : " + location);
loc = location;
locationManager.removeUpdates(listener);
}
};
}
Here is line 137:
mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
.getMap();
Here is line 43: initCompo();
来源：https://stackoverflow.com/questions/24142147/nullpointerexception-trying-to-launch-map-fragment