我有一个发布在Google Play的安卓应用，有一些人报告了这个错误。但我不知道它的含义是什么以及出了什么问题。如果有人能帮助我并告诉我问题所在或者有任何建议，那将非常感激。谢谢你的帮助。
java.lang.NullPointerException
at android.media.MediaPlayer.add_mm_settings(MediaPlayer.java:1855)
at android.media.MediaPlayer.setDataSource(MediaPlayer.java:798)
at android.widget.VideoView.openVideo(VideoView.java:225)
at android.widget.VideoView.access$2000(VideoView.java:49)
at android.widget.VideoView$6.surfaceCreated(VideoView.java:482)
at android.view.SurfaceView.updateWindow(SurfaceView.java:551)
at android.view.SurfaceView.dispatchDraw(SurfaceView.java:348)
at android.view.ViewGroup.drawChild(ViewGroup.java:1730)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.ViewGroup.drawChild(ViewGroup.java:1730)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.ViewGroup.drawChild(ViewGroup.java:1730)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.View.draw(View.java:6973)
at android.widget.FrameLayout.draw(FrameLayout.java:357)
at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1949)
at android.view.ViewRoot.draw(ViewRoot.java:1600)
at android.view.ViewRoot.performTraversals(ViewRoot.java:1321)
at android.view.ViewRoot.handleMessage(ViewRoot.java:1957)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:150)
at android.app.ActivityThread.main(ActivityThread.java:4306)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)