Question

我有Android应用程序，我在我的设备上开发了几个月，可以在API 19上运行。现在，当我使用API 22获得新手机时，所有工作除了谷歌地图。这个API上的谷歌地图有什么特别之处，或者我做错了什么？在应用程序设置中我有

minSdkVersion 15
targetSdkVersion 23

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:23.0.1'
    compile 'com.google.android.gms:play-services:7.8.0'
    //tried this but still wont work    
    //compile 'com.google.android.gms:play-services:8.4.0'     
}

地图活动的代码是，我有评论//发生错误

public class MapLocation extends FragmentActivity {

private GoogleMap mMap; // Might be null if Google Play services APK is not available.
public Double lat;
public Double log;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map_location);
    setUpMapIfNeeded();

    Intent i = getIntent();
    lat = Double.parseDouble(i.getStringExtra("lat"));
    log = Double.parseDouble(i.getStringExtra("log"));
    centerMapOnMyLocation();
}

@Override
protected void onResume() {
    super.onResume();
    setUpMapIfNeeded();
}

private void setUpMapIfNeeded() {

    if (mMap == null) {

        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
               .getMap();            
        if (mMap != null) {
            setUpMap();
        }
    }
}

private void setUpMap() {
    mMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);        
}
private void centerMapOnMyLocation() {

    //HERE is ERROR when checking log of phone
    //HERE is ERROR when checking log of phone
    //HERE is ERROR when checking log of phone
    //HERE is ERROR when checking log of phone


    mMap.setMyLocationEnabled(true);

    if (!(lat == 0.0 || log == 0.0)) {

        CameraUpdate zoom=CameraUpdateFactory.zoomTo(18);

        CameraUpdate myLocation= CameraUpdateFactory.newLatLng(new LatLng(lat,log));

        mMap.moveCamera(myLocation);
        mMap.animateCamera(zoom);
        mMap.addMarker(new MarkerOptions().position(new LatLng(lat, log)).title("Title"));
        Toast.makeText(this, "Map positioned", Toast.LENGTH_LONG).show();
    }
    else
    {
        Toast.makeText(this, "no location", Toast.LENGTH_LONG).show();
    }

}

}

手机记录

java.lang.RuntimeException：无法启动活动ComponentInfo {com.smth / com.smth.MapLocation}：java.lang.NullPointerException：尝试调用虚拟方法'void com.google.android.gms.maps.GoogleMap空集对象引用上的.setMyLocationEnabled（boolean）' 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2325）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2387）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1303）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5255） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:905）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:700）引发者：java.lang.NullPointerException：尝试在空对象引用上调用虚方法'void com.google.android.gms.maps.GoogleMap.setMyLocationEnabled（boolean）' at com.smth.MapLocation.centerMapOnMyLocation（MapLocation.java:83）在com.vodovod.ivan.watercounter.MapLocation.onCreate（MapLocation.java:30）在android.app.Activity.performCreate（Activity.java:6036）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1106）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2278）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2387）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1303）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5255） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:905）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:700）

地图布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 android:keepScreenOn="true">
<fragment 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" android:id="@+id/map"
 tools:context="com.vodovod.ivan.watercounter.MapLocation"
 android:name="com.google.android.gms.maps.SupportMapFragment"
 android:keepScreenOn="true" />
</LinearLayout>

Answer 1

Map无法立即供您使用，这就是为什么它表示您正在调用null对象。实现OnMapReadyCallback接口，从该接口覆盖onMapReady方法，并在该方法中调用涉及Google Map实例的方法。

Answer 2

如@Fustigador所述，您会收到NullPointerException，因为尚未初始化地图对象。要解决您的问题，请将getMap()替换为

getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap map) {
                centerMapOnMyLocation(map);
            }
        });

Android地图适用于API 19但不适用于API 22

2 个答案: