问题
I have a google map in a fragment in my application. Funny thing is that the map loads, but the logcat displays a NullPointerException, and I only noticed it when tried to update the camera on the map so that it could automatically zoom in on the marker. Only then the map will crash. Otherwise, the map loads fine in the fragment but with no marker (even though I am adding one using my current gps location).
EDITED*
I understand that its crashing because the googleMap is null, but I don't understand why it's returning null. The map renders and well I've done this before and it usually crashes at that point. Doesn't render.
Here is the logcat error
05-08 01:30:33.143 30130-30130/com.example.javed_000.famjam E/mapApp﹕ java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.SupportMapFragment.getMap()' on a null object reference
05-08 01:30:33.152 30130-30130/com.example.javed_000.famjam E/MapFragment﹕ lat = 10.7270913 and Long = -61.5544451
05-08 01:30:33.155 30130-30130/com.example.javed_000.famjam D/AndroidRuntime﹕ Shutting down VM
05-08 01:30:33.156 30130-30130/com.example.javed_000.famjam E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.javed_000.famjam, PID: 30130
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.animateCamera(com.google.android.gms.maps.CameraUpdate)' on a null object reference
at com.example.javed_000.famjam.MapFragment.getLocation(MapFragment.java:60)
at com.example.javed_000.famjam.MapFragment.onCreateView(MapFragment.java:33)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:953)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:488)
at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:555)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:514)
at android.support.v4.view.ViewPager.setCurrentItem(ViewPager.java:495)
at com.example.javed_000.famjam.SlidingTabLayout$TabClickListener.onClick(SlidingTabLayout.java:283)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
This is my manifest file
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.javed_000.famjam" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.USE_CREDENTIALS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@drawable/launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyAhgnZ7ESL-EIRS4Da_hGw_7u9IQI3SZE0" />
<activity
android:name=".SignInActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
</activity>
</application>
</manifest>
This is my dependencies in the gradle file
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.0.0'
compile 'com.google.android.gms:play-services:7.0.0'
compile 'com.google.android.gms:play-services-maps:7.0.0'
}
This is my layout file.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/mapView"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
Here is my code snippet from the Map Fragment
private void createMapView(){
try {
if(googleMap == null){
SupportMapFragment smf = (SupportMapFragment) getActivity().getSupportFragmentManager().findFragmentById(R.id.mapView);
googleMap = smf.getMap();
if(googleMap == null) {
Toast.makeText(getActivity().getBaseContext(),
"Error creating map", Toast.LENGTH_SHORT).show();
}
}
} catch (NullPointerException exception){
Log.e("mapApp", exception.toString());
}
}
private void getLocation(){
gps = new GPSTracker(this.getActivity());
if(gps.CanGetLocation()){
latitude = gps.getLatitude();
longitude = gps.getLongitude();
Log.e("MapFragment","lat = " + latitude + " and Long = " + longitude);
addMarker(latitude,longitude);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude,longitude), 12));
} else {
gps.showSettingsAlert();
}
}
private void addMarker(double lat, double lng){
if(googleMap != null){
googleMap.addMarker(new MarkerOptions()
.position(new LatLng(lat, lng))
.title("Marker")
.draggable(true)
);
}
}
回答1:
googleMap = ((SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map)).getMap();
This worked for me. getSupportFragmentManager() seemed to be causing all the crashes.
回答2:
MainActivity.xml :
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.google.android.gms.maps.SupportMapFragment"/>
MainActivity.java :
Private GoogleMap GoogleMap;
googleMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
Here's the permission:
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
And here's the metadata section:
...
<meta-data android:name="com.google.android.maps.v2.API_KEY"
android:value="HERE GOES YOUR API KEY" />
来源：https://stackoverflow.com/questions/30116762/google-map-returning-nullpointerexception-google-maps-android-v2