谷歌地图返回空指针异常谷歌地图Android V2

Question

我的应用程序中有一个fragment 中的google map。有趣的是地图加载了，但是 logcat 显示了一个NullPointerException，我只是在尝试更新地图上的相机时才注意到它，以便它可以自动放大marker。只有这样地图才会崩溃。否则，地图在fragment 中加载良好，但没有marker（即使我使用当前gps location 添加一个）。

已编辑*

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我知道它崩溃是因为googleMap 为空，但我不明白它为什么返回空。地图渲染好，我以前做过，它通常在那个时候崩溃。不渲染。

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这是 logcat 错误

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)

这是我的清单文件

<?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>

这是我在 gradle 文件中的依赖项

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'
}

这是我的布局文件。

<?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>

这是我的地图片段中的代码 sn-p

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)
        );
    }
}

Answer 1

googleMap = ((SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map)).getMap();

这对我有用。 getSupportFragmentManager() 似乎导致了所有的崩溃。

Answer 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();

这里是许可：

<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

这是元数据部分：

...

<meta-data android:name="com.google.android.maps.v2.API_KEY"
           android:value="HERE GOES YOUR API KEY" />

Answer 3

只要像下面那样做

@Override
    public void onMapReady(GoogleMap googleMap) {

        MapsInitializer.initialize(getContext());
        map = googleMap;
        map.setMyLocationEnabled(true);
        // Updates the location and zoom of the MapView
        CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(new LatLng(43.1, -87.9), 10);
        map.animateCamera(cameraUpdate);
    }