您好我的应用程序我正在使用videoview播放m3u8视频网址（IMA SDK的示例播放器）。有时我在设备设置中切换ON closedcaption选项后得到此异常。我不明白我做错了什么。以及如何解决这个问题。 请建议如何解决此问题。 设备信息Android 6.0和设备MOTOG3。
08-04 14:29:32.118: W/System.err(1445): java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.CCParser$CCLineBuilder.setCharAt(int, char)' on a null object reference
08-04 14:29:32.118: W/System.err(1445): at android.media.CCParser$CCMemory.der(ClosedCaptionRenderer.java:613)
08-04 14:29:32.119: W/System.err(1445): at android.media.CCParser.handleCtrlCode(ClosedCaptionRenderer.java:280)
08-04 14:29:32.119: W/System.err(1445): at android.media.CCParser.parse(ClosedCaptionRenderer.java:175)
08-04 14:29:32.119: W/System.err(1445): at android.media.ClosedCaptionTrack.onData(ClosedCaptionRenderer.java:93)
08-04 14:29:32.119: W/System.err(1445): at android.media.SubtitleTrack.onData(SubtitleTrack.java:81)
08-04 14:29:32.119: W/System.err(1445): at android.media.MediaPlayer$1.onSubtitleData(MediaPlayer.java:2192)
08-04 14:29:32.119: W/System.err(1445): at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:2949)
08-04 14:29:32.119: W/System.err(1445): at android.os.Handler.dispatchMessage(Handler.java:102)
08-04 14:29:32.119: W/System.err(1445): at android.os.Looper.loop(Looper.java:148)
08-04 14:29:32.119: W/System.err(1445): at android.app.ActivityThread.main(ActivityThread.java:5443)
08-04 14:29:32.119: W/System.err(1445): at java.lang.reflect.Method.invoke(Native Method)
08-04 14:29:32.119: W/System.err(1445): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
08-04 14:29:32.119: W/System.err(1445): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)