问题
After going through SO questions relating to my title, I couldn't find a solution to the problem. I am having a NullPointerException at mapFragment.getMapAsync. Below is my MapActivity code.
package com.example.jerofad.mylocation;
import android.app.FragmentManager;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
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.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
@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) this.getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
// Add a marker in Sydney and move the camera
LatLng sydney = new LatLng(-34, 151);
mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
mMap.getUiSettings().setZoomControlsEnabled(true);
}
}
I am using google play service 8.4.0. My Android Manifest is given below.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.jerofad.mylocation">
<!--
The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
Google Maps Android API v2, but you must specify either coarse or fine
location permissions for the 'MyLocation' functionality.
-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
android:maxSdkVersion="22"/>
<permission
android:name="com.example.jerofad.mylocation.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-permission android:name="com.example.jerofad.mylocation.permission.MAPS_RECEIVE" />
<uses-permission
android:name="android.permission.READ_EXTERNAL_STORAGE"
android:maxSdkVersion="22" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<application
android:allowBackup="true"
android:icon="@drawable/mylocation"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<meta-data
android:name="com.google.android.geo.API_KEY"
android:value="@string/google_maps_key" />
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<activity
android:name=".MapsActivity"
android:label="@string/title_activity_maps">
</activity>
<activity
android:name=".LauncherActivity"
android:label="@string/title_activity_launcher"
android:theme="@style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
How can I fix the error at mapFragment.getMapAsync(this). Thanks in advance. Here is the crash Log.
04-25 11:11:49.079 31448-31448/com.example.jerofad.mylocation
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.jerofad.mylocation, PID: 31448
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.jerofad.mylocation/com.example.jerofad.mylocation.MapsActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5299)
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:825)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.jerofad.mylocation.MapsActivity.onCreate(MapsActivity.java:24)
at android.app.Activity.performCreate(Activity.java:5423)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5299)
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:825)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
at dalvik.system.NativeStart.main(Native Method)
Here is the activity_maps.xml.
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map"
class ="com.google.android.gms.maps.MapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.example.jerofad.mylocation.MapsActivity" />
回答1:
Please try this,
Remove/comment SupportMapfragment line for a while and Try this,
MapFragment mapFragment = (MapFragment) getFragmentManager() .findFragmentById(R.id.map);
回答2:
You've two options, One is as Raghavendra told another one is you can change the class attribute
class ="com.google.android.gms.maps.MapFragment"
to
class="com.google.android.gms.maps.SupportMapFragment"
Then your codes will work.
回答3:
U can try this.. it might help...
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Log.i("onActivityCreated", "onActivityCreated");
if(supportMapFragment==null){
supportMapFragment = (SupportMapFragment)getChildFragmentManager().findFragmentById(R.id.map);
supportMapFragment.getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap googleMap) {
mGoogleMap = googleMap;
loadMapAtPosition(googleMap, CAMERA_INITIAL_LATITUDE, CAMERA_INITIAL_LONGITUDE);
}
});
}
回答4:
If this might help anybody..
Add < uses-permission> NETWORK_ACCESS_STATE to your Manifest.
来源：https://stackoverflow.com/questions/36832035/nullpointerexception-at-mapfragment-getmapasync