java.lang.RuntimeException：無法在Android版本4上啓動活動ComponentInfo。+

-1

我在Android versions 4.+（特別是在4.1和4.3）中遇到此錯誤，而沒有在任何其他版本的android中出現此錯誤。活動和庫（我使用GooglePlayServices和YouTubePlayerAPI）在Manifest.xml文件和gradle文件中引用。java.lang.RuntimeException：無法在Android版本4上啓動活動ComponentInfo。+

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.test/com.app.test.DetailActivity}: java.lang.NullPointerException 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
at android.app.ActivityThread.access$600(ActivityThread.java:141) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:5039) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
at com.app.test.content.FirstFragment.onCreate(FirstFragment.java:151) 
at android.support.v4.app.Fragment.performCreate(Fragment.java:1763) 
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:913) 
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126) 
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108) 
at android.support.v4.app.FragmentManagerImpl.dispatchCreate(FragmentManager.java:1912) 
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:266) 
at com.app.test.DetailActivity.onCreate(DetailActivity.java:73) 
at android.app.Activity.performCreate(Activity.java:5104) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
... 11 more

從片段，其中該錯誤引起的（線151）的代碼是該片段的onCreate（）方法附：

@Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setHasOptionsMenu(true); 

     if(getArguments() != null && getArguments().containsKey(ARG_ITEM_ID)) { 
      // Loads the content specified by the fragment arguments. 
      mItem = Items.getInstance().getMap().get(getArguments().getString(ARG_ITEM_ID)); 
     } 

     // Initialize mCustomMediaPlayer 
     mCustomMediaPlayer = new CustomMediaPlayer(getActivity().getApplicationContext(), mItem.getTrackId()); 
    }

凡尖線151是：

mCustomMediaPlayer = new CustomMediaPlayer(VillancicosActivity.getContext(), mItem.getTrackId());

CustomMediaPlayer類別：

public class CustomMediaPlayer { 

    /////// Constants 

    private static final String TAG = "CustomMediaPlayer"; 

    /////// Fields 

    /** 
    * The application context. 
    * Is used to manage MediaPlayer and async class. 
    */ 
    private Context mContext; 

    /** 
    * MediaPlayer instance. 
    */ 
    private MediaPlayer mMediaPlayer; 

    /** 
    * The id representing track used in MediaPlayer create() method 
    * where will be played. 
    */ 
    private Integer mTrackId; 

    /** 
    * A flag indicating if the track is playing or not. 
    */ 
    private Boolean mIsPlaying = false; 

    /** 
    * Initialize providing the application context and the calling fragment track id. 
    * 
    * @param context The Context to use. 
    * @param trackId The raw resource id to use as datasource. 
    */ 
    public CustomMediaPlayer(Context context, Integer trackId) { 
     mContext = context; 
     mTrackId = trackId; 
    } 

..... 
}

這是類的一部分，主構造函數從第151行的FirstFragment中調用。

任何想法？謝謝大家！

來源

2014-12-22 GmloMalo

可能'mItem'爲空。 'VillancicosActivity.getContext（）'味道也非常糟糕。 – laalto

我已經嘗試getActivity（）。getApplicationContext（）並獲取相同的錯誤報告。 – GmloMalo

我想如果它是在獲取上下文，它不會在任何Android版本，不僅在4 + – GmloMalo

試試這個

mCustomMediaPlayer = new CustomMediaPlayer(getActivity(), mItem.getTrackId());

，並檢查mItem ==null與否。

來源

2014-12-22 13:12:26

我已經試過它和mItem在一些設備與Android 2.3.3和2.3.7爲空，但我不知道是什麼原因 – GmloMalo

您的活動無法識別Villancicos Activity.getContext（）您需要傳遞一個有效的上下文。嘗試getApplicationContext（）代替。

來源

2014-12-22 13:19:02

我試過getActivity（）。getApplicationContext（）也有同樣的錯誤。 – GmloMalo

你檢查過mItem！= null嗎？ –

java.lang.RuntimeException：無法在Android版本4上啓動活動ComponentInfo。+

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