Play from a URI available locally in the system :
public void playAudio(View view) {
Uri myUri =Uri.parse("/storage/sdcard1/download/Motta_Modatisari.mp3");
MediaPlayer mediaPlayer = new MediaPlayer();
mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
mediaPlayer.setDataSource(getApplicationContext(), myUri);
mediaPlayer.prepare();
} catch (IOException e) {
e.printStackTrace();
}
mediaPlayer.start();
}
source: https://developer.android.com/guide/topics/media/mediaplayer.html