Codigo de ejemplo de AsynkTask

AsynkTaskMainActivity

package com.asynctaskdemo;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {
	
	MainActivity yo;
	
	TextView tv;
	Button but;
	Integer ejecuciones = new Integer(20);
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        yo = this;
        
        this.tv = (TextView) this.findViewById(R.id.texto);
        this.but =  (Button) this.findViewById(R.id.but);
        
        this.but.setOnClickListener(new OnClickListener(){

			public void onClick(View v) {
				DownloadFilesTask d = new DownloadFilesTask();
				d.activityPadre = yo;
				d.execute(ejecuciones);
			}
        	
        });
        /*
        this.but.setOnClickListener(new OnClickListener(){

			public void onClick(View v) {
				new Thread(new Runnable() {
				    public void run() {
				    	for (int i = 0; i < ejecuciones.intValue(); i++) {
			            	SystemClock.sleep(250);
			            }
				    }
				  }).start();
			}
        	
        });
        */
    }
    
    private class DownloadFilesTask extends AsyncTask<Integer, Integer, Long> {
    		public MainActivity activityPadre;
        protected Long doInBackground(Integer... inte) {

            for (int i = 0; i < inte[0]; i++) {
            	SystemClock.sleep(250);
            	publishProgress((int) ((i / (float) inte[0]) * 100));
            }
            return new Long(0);
        }

        protected void onProgressUpdate(Integer... progress) {
            tv.setText(""+(progress[0]));
        }

        protected void onPostExecute(Long result) {
            Log.i("MyLog","Downloaded " + result + " bytes");
        }
    }
}