MapView類的NullPointerException在的onCreate

我創建一個MapView程序是這樣的：MapView類的NullPointerException在的onCreate

MapView mv = new MapView(this);

然而，這導致了NullPointerException（查看日誌）。如果我使用另一個構造函數，如

MapView mv = new MapView(this, new GoogleMapOptions());

一切都很好。有什麼事？

的onCreate：

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

    mSmallMapView = new MapView(this); 
    mSmallMapView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, 200)); 

    this.addView(mSmallMapView); 

    mSmallMapView.onCreate(savedInstanceState); 
}

logcat的：

01-19 01:28:20.411: E/AndroidRuntime(16039): FATAL EXCEPTION: main 
01-19 01:28:20.411: E/AndroidRuntime(16039): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example/com.example.ui.ListingsActivity}: java.lang.NullPointerException 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread.access$600(ActivityThread.java:141) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.os.Handler.dispatchMessage(Handler.java:99) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.os.Looper.loop(Looper.java:137) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread.main(ActivityThread.java:5039) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at java.lang.reflect.Method.invokeNative(Native Method) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at java.lang.reflect.Method.invoke(Method.java:511) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at dalvik.system.NativeStart.main(Native Method) 
01-19 01:28:20.411: E/AndroidRuntime(16039): Caused by: java.lang.NullPointerException 
01-19 01:28:20.411: E/AndroidRuntime(16039): at maps.am.r.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at maps.y.ae.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at maps.y.bm.onCreate(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.internal.IMapViewDelegate$Stub.onTransact(IMapViewDelegate.java:66) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.os.Binder.transact(Binder.java:310) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.internal.IMapViewDelegate$a$a.onCreate(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.MapView$b.onCreate(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.internal.d$3.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.internal.i.b(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.MapView$a.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.MapView$a.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.internal.d.a(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.internal.d.onCreate(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.google.android.gms.maps.MapView.onCreate(Unknown Source) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at com.example.ui.ListingsActivity.onCreate(ListingsActivity.java:108) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.Activity.performCreate(Activity.java:5104) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
01-19 01:28:20.411: E/AndroidRuntime(16039): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
01-19 01:28:20.411: E/AndroidRuntime(16039): ... 11 more

來源

2013-01-19 Max

把你的oncreate方法放在這裏 –

你的活動擴展了'MapActivity'嗎？ – tolgap

哦，我應該說我正在使用'Google Maps Android API v2'，我認爲沒有像'MapActivity'這樣的東西......還有，正如我所提到的，使用其他構造函數，一切都很完美。我只是想知道這是否是我的錯，這是一個錯誤。 – Max

你可能需要初始化地圖爲了這個工作。

嘗試調用：

try { 
    MapsInitializer.initialize(getActivity()); 
} catch (GooglePlayServicesNotAvailableException e) { 
    e.printStackTrace(); 
}

在onCreate（）方法只是後 '的setContentView（）'。

來源

2013-01-30 01:02:16 Scott

MapView類的NullPointerException在的onCreate

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