Android : 効果音の鳴らし方

PlaceholderFragment.java

public class PlaceholderFragment extends Fragment {
    private MediaPlayer mp;
      public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mp = MediaPlayer.create(getActivity().getApplicationContext(), R.raw.decision17);
        
          View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        ButterKnife.inject(this, rootView);
        return rootView;
    }

    @Override
    public void onDestroyView() {
        ButterKnife.reset(this);
        mp.release();
        super.onDestroyView();
    }

    @OnClick(R.id.button)
    public void onButtonClicked() {
        mp.start();
    }
}