Generic Android Async Task with internal interface

BoilerPipeTask.java

package com.example.toniotest.utils;

import android.os.AsyncTask;

/**
 * Created by gnuton on 5/22/13.
 */
public class BoilerPipeTask extends AsyncTask<String, Void, String> {
    private static final String TAG = "BOILER PIPE TASK";

    private static OnBoilerplateRemovedListener listener;

    public interface OnBoilerplateRemovedListener {
        public void onBoilerplageRemoved(final String buffer);
    }

    public BoilerPipeTask(Object o) {
        if (o instanceof OnBoilerplateRemovedListener) {
            this.listener = (OnBoilerplateRemovedListener) o;
        } else {
            throw new ClassCastException(o.toString() + " must implement BoilerPipeTask.OnBoilerplateRemovedListener");
        }
    }

    @Override
    protected String doInBackground(String... strings) {

        return null;
    }

    @Override
    protected void onPostExecute(String s) {
        listener.onBoilerplageRemoved(s);
    }
}