Java Example

• iterators

  • iterators/FacebookIterator.java

    package refactoring_guru.iterator.example.iterators;
    
    import refactoring_guru.iterator.example.profile.Profile;
    import refactoring_guru.iterator.example.social_networks.Facebook;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class FacebookIterator implements ProfileIterator {
        private Facebook facebook;
        private String type;
        private String email;
        private int currentPosition = 0;
        private List<String> emails = new ArrayList<>();
        private List<Profile> profiles = new ArrayList<>();
    
        public FacebookIterator(Facebook facebook, String type, String email) {
            this.facebook = facebook;
            this.type = type;
            this.email = email;
        }
    
        private void lazyLoad() {
            if (emails.size() == 0) {
                List<String> profiles = facebook.requestProfileFriendsFromFacebook(this.email, this.type);
                for (String profile : profiles) {
                    this.emails.add(profile);
                    this.profiles.add(null);
                }
            }
        }
    
        @Override
        public boolean hasNext() {
            lazyLoad();
            return currentPosition < emails.size();
        }
    
        @Override
        public Profile getNext() {
            if (!hasNext()) {
                return null;
            }
    
            String friendEmail = emails.get(currentPosition);
            Profile friendProfile = profiles.get(currentPosition);
            if (friendProfile == null) {
                friendProfile = facebook.requestProfileFromFacebook(friendEmail);
                profiles.set(currentPosition, friendProfile);
            }
            currentPosition++;
            return friendProfile;
        }
    
        @Override
        public void reset() {
            currentPosition = 0;
        }
    }

  • iterators/LinkedInIterator.java

    package refactoring_guru.iterator.example.iterators;
    
    import refactoring_guru.iterator.example.profile.Profile;
    import refactoring_guru.iterator.example.social_networks.LinkedIn;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class LinkedInIterator implements ProfileIterator {
        private LinkedIn linkedIn;
        private String type;
        private String email;
        private int currentPosition = 0;
        private List<String> emails = new ArrayList<>();
        private List<Profile> contacts = new ArrayList<>();
    
        public LinkedInIterator(LinkedIn linkedIn, String type, String email) {
            this.linkedIn = linkedIn;
            this.type = type;
            this.email = email;
        }
    
        private void lazyLoad() {
            if (emails.size() == 0) {
                List<String> profiles = linkedIn.requestRelatedContactsFromLinkedInAPI(this.email, this.type);
                for (String profile : profiles) {
                    this.emails.add(profile);
                    this.contacts.add(null);
                }
            }
        }
    
        @Override
        public boolean hasNext() {
            lazyLoad();
            return currentPosition < emails.size();
        }
    
        @Override
        public Profile getNext() {
            if (!hasNext()) {
                return null;
            }
    
            String friendEmail = emails.get(currentPosition);
            Profile friendContact = contacts.get(currentPosition);
            if (friendContact == null) {
                friendContact = linkedIn.requestContactInfoFromLinkedInAPI(friendEmail);
                contacts.set(currentPosition, friendContact);
            }
            currentPosition++;
            return friendContact;
        }
    
        @Override
        public void reset() {
            currentPosition = 0;
        }
    }

  • iterators/ProfileIterator.java

    package refactoring_guru.iterator.example.iterators;
    
    import refactoring_guru.iterator.example.profile.Profile;
    
    public interface ProfileIterator {
        boolean hasNext();
    
        Profile getNext();
    
        void reset();
    }

• profile

  • profile/Profile.java

    package refactoring_guru.iterator.example.profile;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class Profile {
        private String name;
        private String email;
        private Map<String, List<String>> contacts = new HashMap<>();
    
        public Profile(String email, String name, String... contacts) {
            this.email = email;
            this.name = name;
    
            // Parse contact list from a set of "friend:email@gmail.com" pairs.
            for (String contact : contacts) {
                String[] parts = contact.split(":");
                String contactType = "friend", contactEmail;
                if (parts.length == 1) {
                    contactEmail = parts[0];
                }
                else {
                    contactType = parts[0];
                    contactEmail = parts[1];
                }
                if (!this.contacts.containsKey(contactType)) {
                    this.contacts.put(contactType, new ArrayList<>());
                }
                this.contacts.get(contactType).add(contactEmail);
            }
        }
    
        public String getEmail() {
            return email;
        }
    
        public String getName() {
            return name;
        }
    
        public List<String> getContacts(String contactType) {
            if (!this.contacts.containsKey(contactType)) {
                this.contacts.put(contactType, new ArrayList<>());
            }
            return contacts.get(contactType);
        }
    }

• social_networks

  • social_networks/Facebook.java

    package refactoring_guru.iterator.example.social_networks;
    
    import refactoring_guru.iterator.example.iterators.FacebookIterator;
    import refactoring_guru.iterator.example.iterators.ProfileIterator;
    import refactoring_guru.iterator.example.profile.Profile;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class Facebook implements SocialNetwork {
        private List<Profile> profiles;
    
        public Facebook(List<Profile> cache) {
            if (cache != null) {
                this.profiles = cache;
            } else {
                this.profiles = new ArrayList<>();
            }
        }
    
        public Profile requestProfileFromFacebook(String profileEmail) {
            // Here would be a POST request to one of the Facebook API endpoints.
            // Instead, we emulates long network connection, which you would expect
            // in the real life...
            simulateNetworkLatency();
            System.out.println("Facebook: Loading profile '" + profileEmail + "' over the network...");
    
            // ...and return test data.
            return findProfile(profileEmail);
        }
    
        public List<String> requestProfileFriendsFromFacebook(String profileEmail, String contactType) {
            // Here would be a POST request to one of the Facebook API endpoints.
            // Instead, we emulates long network connection, which you would expect
            // in the real life...
            simulateNetworkLatency();
            System.out.println("Facebook: Loading '" + contactType + "' list of '" + profileEmail + "' over the network...");
    
            // ...and return test data.
            Profile profile = findProfile(profileEmail);
            if (profile != null) {
                return profile.getContacts(contactType);
            }
            return null;
        }
    
        private Profile findProfile(String profileEmail) {
            for (Profile profile : profiles) {
                if (profile.getEmail().equals(profileEmail)) {
                    return profile;
                }
            }
            return null;
        }
    
        private void simulateNetworkLatency() {
            try {
                Thread.sleep(2500);
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
    
        @Override
        public ProfileIterator createFriendsIterator(String profileEmail) {
            return new FacebookIterator(this, "friends", profileEmail);
        }
    
        @Override
        public ProfileIterator createCoworkersIterator(String profileEmail) {
            return new FacebookIterator(this, "coworkers", profileEmail);
        }
    
    }

  • social_networks/LinkedIn.java

    package refactoring_guru.iterator.example.social_networks;
    
    import refactoring_guru.iterator.example.iterators.LinkedInIterator;
    import refactoring_guru.iterator.example.iterators.ProfileIterator;
    import refactoring_guru.iterator.example.profile.Profile;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class LinkedIn implements SocialNetwork {
        private List<Profile> contacts;
    
        public LinkedIn(List<Profile> cache) {
            if (cache != null) {
                this.contacts = cache;
            } else {
                this.contacts = new ArrayList<>();
            }
        }
    
        public Profile requestContactInfoFromLinkedInAPI(String profileEmail) {
            // Here would be a POST request to one of the LinkedIn API endpoints.
            // Instead, we emulates long network connection, which you would expect
            // in the real life...
            simulateNetworkLatency();
            System.out.println("LinkedIn: Loading profile '" + profileEmail + "' over the network...");
    
            // ...and return test data.
            return findContact(profileEmail);
        }
    
        public List<String> requestRelatedContactsFromLinkedInAPI(String profileEmail, String contactType) {
            // Here would be a POST request to one of the LinkedIn API endpoints.
            // Instead, we emulates long network connection, which you would expect
            // in the real life.
            simulateNetworkLatency();
            System.out.println("LinkedIn: Loading '" + contactType + "' list of '" + profileEmail + "' over the network...");
    
            // ...and return test data.
            Profile profile = findContact(profileEmail);
            if (profile != null) {
                return profile.getContacts(contactType);
            }
            return null;
        }
    
        private Profile findContact(String profileEmail) {
            for (Profile profile : contacts) {
                if (profile.getEmail().equals(profileEmail)) {
                    return profile;
                }
            }
            return null;
        }
    
        private void simulateNetworkLatency() {
            try {
                Thread.sleep(2500);
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
    
        @Override
        public ProfileIterator createFriendsIterator(String profileEmail) {
            return new LinkedInIterator(this, "friends", profileEmail);
        }
    
        @Override
        public ProfileIterator createCoworkersIterator(String profileEmail) {
            return new LinkedInIterator(this, "coworkers", profileEmail);
        }
    }

  • social_networks/SocialNetwork.java

    package refactoring_guru.iterator.example.social_networks;
    
    import refactoring_guru.iterator.example.iterators.ProfileIterator;
    
    public interface SocialNetwork {
        ProfileIterator createFriendsIterator(String profileEmail);
    
        ProfileIterator createCoworkersIterator(String profileEmail);
    }

• spammer

  • spammer/SocialSpammer.java

    package refactoring_guru.iterator.example.spammer;
    
    import refactoring_guru.iterator.example.iterators.ProfileIterator;
    import refactoring_guru.iterator.example.profile.Profile;
    import refactoring_guru.iterator.example.social_networks.SocialNetwork;
    
    public class SocialSpammer {
        public SocialNetwork network;
        public ProfileIterator iterator;
    
        public SocialSpammer(SocialNetwork network) {
            this.network = network;
        }
    
        public void sendSpamToFriends(String profileEmail, String message) {
            System.out.println("\nIterating over friends...\n");
            iterator = network.createFriendsIterator(profileEmail);
            while (iterator.hasNext()) {
                Profile profile = iterator.getNext();
                sendMessage(profile.getEmail(), message);
            }
        }
    
        public void sendSpamToCoworkers(String profileEmail, String message) {
            System.out.println("\nIterating over coworkers...\n");
            iterator = network.createCoworkersIterator(profileEmail);
            while (iterator.hasNext()) {
                Profile profile = iterator.getNext();
                sendMessage(profile.getEmail(), message);
            }
        }
    
        public void sendMessage(String email, String message) {
            System.out.println("Sent message to: '" + email + "'. Message body: '" + message + "'");
        }
    }

• Demo.java

package refactoring_guru.iterator.example;

import refactoring_guru.iterator.example.profile.Profile;
import refactoring_guru.iterator.example.social_networks.Facebook;
import refactoring_guru.iterator.example.social_networks.LinkedIn;
import refactoring_guru.iterator.example.social_networks.SocialNetwork;
import refactoring_guru.iterator.example.spammer.SocialSpammer;

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

/**
 * Demo class. Everything comes together here.
 */
public class Demo {
    public static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        System.out.println("Please specify social network to target spam tool (default:Facebook):");
        System.out.println("1. Facebook");
        System.out.println("2. LinkedIn");
        String choice = scanner.nextLine();

        SocialNetwork network;
        if (choice.equals("2")) {
            network = new LinkedIn(createTestProfiles());
        }
        else {
            network = new Facebook(createTestProfiles());
        }

        SocialSpammer spammer = new SocialSpammer(network);
        spammer.sendSpamToFriends("anna.smith@bing.com",
                "Hey! This is Anna's friend Josh. Can you do me a favor and like this post [link]?");
        spammer.sendSpamToCoworkers("anna.smith@bing.com",
                "Hey! This is Anna's boss Jason. Anna told me you would be interested in [link].");
    }

    public static List<Profile> createTestProfiles() {
        List<Profile> data = new ArrayList<Profile>();
        data.add(new Profile("anna.smith@bing.com", "Anna Smith", "friends:mad_max@ya.com", "friends:catwoman@yahoo.com", "coworkers:sam@amazon.com"));
        data.add(new Profile("mad_max@ya.com", "Maximilian", "friends:anna.smith@bing.com", "coworkers:sam@amazon.com"));
        data.add(new Profile("bill@microsoft.eu", "Billie", "coworkers:avanger@ukr.net"));
        data.add(new Profile("avanger@ukr.net", "John Day", "coworkers:bill@microsoft.eu"));
        data.add(new Profile("sam@amazon.com", "Sam Kitting", "coworkers:anna.smith@bing.com", "coworkers:mad_max@ya.com", "friends:catwoman@yahoo.com"));
        data.add(new Profile("catwoman@yahoo.com", "Liza", "friends:anna.smith@bing.com", "friends:sam@amazon.com"));
        return data;
    }
}

Please specify social network to target spam tool (default:Facebook):
1. Facebook
2. LinkedIn
> 1

Iterating over friends...

Facebook: Loading 'friends' list of 'anna.smith@bing.com' over the network...
Facebook: Loading profile 'mad_max@ya.com' over the network...
Sent message to: 'mad_max@ya.com'. Message body: 'Hey! This is Anna's friend Josh. Can you do me a favor and like this post [link]?'
Facebook: Loading profile 'catwoman@yahoo.com' over the network...
Sent message to: 'catwoman@yahoo.com'. Message body: 'Hey! This is Anna's friend Josh. Can you do me a favor and like this post [link]?'

Iterating over coworkers...

Facebook: Loading 'coworkers' list of 'anna.smith@bing.com' over the network...
Facebook: Loading profile 'sam@amazon.com' over the network...
Sent message to: 'sam@amazon.com'. Message body: 'Hey! This is Anna's boss Jason. Anna told me you would be interested in [link].'