android求告知报出来的这是什么错误？？完全没提到自己的代码啊

10-07 21:05:32.704  22810-22810/com.seedxyx.noteinfingers E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.ViewGroup.dispatchVisibilityChanged(ViewGroup.java:1029)
            at android.view.View.setFlags(View.java:8370)
            at android.view.View.setVisibility(View.java:5512)
            at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2638)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2097)
            at android.app.ActivityThread.access$600(ActivityThread.java:133)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1203)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4794)
            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:789)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
            at dalvik.system.NativeStart.main(Native Method)

app突然就刚进去就崩溃了，这是个什么错误？