我想在广告关闭后更改fragment。但是它抛出一个IllegalStateExceptionfragment1:...mInterstitialAd=newInterstitialAd(this.getContext());mInterstitialAd.setAdUnitId("ca-app-pub-3940256099942544/1033173712");mInterstitialAd.setAdListener(newAdListener(){@OverridepublicvoidonAdClosed(){masterActivity.showGame();//MasterA