MediaPlayer create method return null object Android

问题

I followed many guides about the music player, but my problem is the create method because when i try to do start() the activity crash saying to me that musicplayer is null, here is the code:

MediaPlayer mediaPlayer;
mediaPlayer = MediaPlayer.create(CustomMediaPlayer.this, R.raw.aud_0101);
...
mediaPlayer.start();

the audio file is right inside the raw directory, so I don't know how could be the problem of this nullPointer, anyone have some idea?

来源：https://stackoverflow.com/questions/34881160/mediaplayer-create-method-return-null-object-android