问题
I'm trying to convert a google map activity to work inside a fragment that will be called in NavigationView.
The map is showing but when i used the code getMapAsync
mFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
mFragment.getMapAsync(this);
I got an error message
E/AndroidRuntime: FATAL EXCEPTION: main
E/AndroidRuntime: java.lang.NullPointerException
E/AndroidRuntime: at com.sample.samplemap.samplemapFragment.onCreate(samplemapFragment.java:32)
E/AndroidRuntime: at android.support.v4.app.Fragment.performCreate(Fragment.java:1942)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1259)
E/AndroidRuntime: at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1624)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
E/AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:725)
E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime: at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5306)
E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
samplemapFragment.java
package com.sample.samplemap;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
public class samplemapFragment extends Fragment implements OnMapReadyCallback {
GoogleMap mGoogleMap;
SupportMapFragment mFragment;
public samplemapFragment() {
Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
mFragment.getMapAsync(this);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_sample_map, container, false);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mGoogleMap = googleMap;
mGoogleMap.setMyLocationEnabled(true);
}
}
fragment_sample_map.xml
<RelativeLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
tools:context="com.sample.samplemap.samplemapFragment"
xmlns:tools="http://schemas.android.com/tools">
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto" android:layout_width="384dp"
android:layout_height="300dp" android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_marginTop="44dp"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
回答1:
I have checked that the LifeCycle of the Fragment is: https://developer.xamarin.com/guides/android/platform_features/fragments/part_1_-_creating_a_fragment/Images/fragment_lifecycle.png
OnCreate will Call First then OnCreateView.
As I have implemented code for you that works fine here with MapView:
MapCheckingActivity.java
package com.ramesh.expandablelistview;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
public class MapCheckingActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map_checking);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportFragmentManager().beginTransaction()
.replace(R.id.content_frame,
new SampleMapFragment()).commit();
}
}
SampleMapFragment.java
package com.ramesh.expandablelistview;
/**
* Created by Ramesh Kumar on 2/17/2016.
*/
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.MapsInitializer;
import com.google.android.gms.maps.OnMapReadyCallback;
public class SampleMapFragment extends Fragment implements
OnMapReadyCallback {
GoogleMap mGoogleMap;
MapView mapView;
View mView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MapsInitializer.initialize(getContext());
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
mView = inflater.inflate(R.layout.fragment_map, container, false);
return mView;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mapView = (MapView) mView.findViewById(R.id.map);
if (mapView != null) {
// Initialise the MapView
mapView.onCreate(null);
mapView.onResume();
// Set the map ready callback to receive the GoogleMap object
mapView.getMapAsync(this);
}
}
@Override
public void onMapReady(GoogleMap googleMap) {
MapsInitializer.initialize(getContext());
mGoogleMap = googleMap;
mGoogleMap.setMyLocationEnabled(true);
}
}
activity_map_checking.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:fitsSystemWindows="true"
tools:context="com.ramesh.expandablelistview.MapCheckingActivity">
<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar android:id="@+id/toolbar"
android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_map_checking" />
<android.support.design.widget.FloatingActionButton android:id="@+id/fab"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin"
android:src="@android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
content_map_checking.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_map_checking"
tools:context="com.ramesh.expandablelistview.MapCheckingActivity">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/content_frame"/>
</RelativeLayout>
fragment_map.xml:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.sample.samplemap.samplemapFragment">
<!--<fragment xmlns:android="http://schemas.android.com/apk/res/android"-->
<!--xmlns:map="http://schemas.android.com/apk/res-auto" android:layout_width="384dp"-->
<!--android:layout_height="300dp" android:id="@+id/map"-->
<!--android:name="com.google.android.gms.maps.SupportMapFragment"-->
<!--android:layout_marginTop="44dp"-->
<!--android:layout_alignParentTop="true" />-->
<com.google.android.gms.maps.MapView
android:id="@+id/map" android:layout_marginTop="44dp"
android:layout_width="384dp" android:layout_height="300dp"/>
</RelativeLayout>
I have created map with in the Fragment by MapView.
In Menifest:
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="@string/google_maps_key" />
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
Map is not showing because of HashKey I entered wrong If it helps then Accept it as Answer. Thanks
来源：https://stackoverflow.com/questions/35458584/google-map-inside-another-fragment-error-when-calling-getmapasync