Thread: I got this error and I don't know how to resolve this

I got this error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.MediaController.setAnchorView(andro id.view.View)' on a null object reference

This is my code

 
public class SymptomArrayAdapter extends ArrayAdapter<Symptom> {
 
    private MediaController mc;
 
    public SymptomArrayAdapter(Context context, List<Symptom> objects) {
        super(context, -1, objects);
    }
 
    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
 
        LayoutInflater layoutInflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 
        View listViewItem = layoutInflater.inflate(R.layout.symptomlistitem, parent, false);
        TextView txtSymptom = (TextView)listViewItem.findViewById(R.id.txtSymptom);
        final VideoView videoSymptom = (VideoView) listViewItem.findViewById(R.id.videoSymptom);
 
        Symptom symptom = this.getItem(position);
 
        txtSymptom.setText(symptom.getSymptom());
        videoSymptom.setVideoURI(Uri.parse("android.resource://com.example.speechrecogniser/" + (symptom.getVideo())));
        videoSymptom.setVisibility(View.VISIBLE);
        videoSymptom.setMediaController(mc);
        videoSymptom.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                videoSymptom.start();
            }
        });
        mc.setAnchorView(videoSymptom);
        return listViewItem;
    }
}