Callback on Java

Callback.java

package com.nevacom.vigi.intface;

public interface Callback<T> {
	public void invoke(T arg);
}

FacebookDAO.java

/*
 * Mi capa que hará las consultas a facebook
 */
 
package com.nevacom.vigi.dao;

import java.util.ArrayList;
import java.util.List;

import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.model.GraphUser;
import com.nevacom.vigi.intface.Callback;
import com.nevacom.vigi.model.Friends;

public class FacebookDAO {

	public void getFacebookFriends(final Callback<Friends> callback) {
		
		Session session = Session.getActiveSession();
		
		Request.newMyFriendsRequest(session, new Request.GraphUserListCallback() {
			
			@Override
			public void onCompleted(List<GraphUser> users, Response response) {
				// TODO Auto-generated method stub
				ArrayList<Friends> friends = new ArrayList<Friends>();
				Friends f = new Friends();
				f.setName("funciona el callback");
				callback.invoke(f);
			}
		}).executeAsync();
		
	}
	
	
}

FriendActivity.java

package com.nevacom.vigi;

import java.util.ArrayList;

import com.nevacom.vigi.dao.FacebookDAO;
import com.nevacom.vigi.helpers.Util;
import com.nevacom.vigi.intface.Callback;
import com.nevacom.vigi.model.Friends;

import android.app.Activity;
import android.content.ContentResolver;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.Menu;

public class FriendActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_friend);
		
		ArrayList<Friends> friendsPhone = this.readContacts();
		
		Util.Log("Facebook Friends!");
		// Llamamos a nuestra clase FacebookDAO
		FacebookDAO facebook = new FacebookDAO();
		// Nuestro callback wiiii :)
		facebook.getFacebookFriends(new Callback<Friends>() {
			
			@Override
			public void invoke(Friends arg) {
				// TODO Auto-generated method stub
				// Aquí recuperamos nuestra data y hacemos lo que se nos da la gana con eso :)
				Util.Log(arg.getName());
				System.out.println("Progress" + arg.getName());
			}
		});
		
	}
	
	private ArrayList<Friends> readContacts() {
		ContentResolver cr = getContentResolver();
		Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);
		ArrayList<Friends> friends = new ArrayList<Friends>();
		
		if(cur.getCount() > 0) {
			while(cur.moveToNext()) {
				int hasPhone = Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)));
				
				if(hasPhone > 0) {
					Friends friend = new Friends();
					friend.setUid(cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID)));
					friend.setName(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)));
					friend.setFacebook(0);
					friends.add(friend);
				}	
			}
		}
		
		return friends;
	}
	
	private ArrayList<Friends> readFacebookFriends() {
		ArrayList<Friends> friends = new ArrayList<Friends>();
		
		
		return friends;
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.friend, menu);
		return true;
	}

}