Code for LinkedIn

We've gone over the different aspects of LinkedIn and observed the attributes attached to the problem using various UML diagrams. Let’s explore the more practical side of things, where we will work on implementing the LinkedIn network using multiple languages. This is usually the last step in an object-oriented design interview process.

We have chosen the following languages to write the skeleton code of the different classes present in LinkedIn:

Java
C#
Python
C++
JavaScript

LinkedIn classes#

In this section, we will provide the skeleton code of the classes designed in the class diagram lesson.

Note: For simplicity, we are not defining getter and setter functions. The reader can assume that all class attributes are private and accessed through their respective public getter methods and modified only through their public method functions.

Constants#

The following code provides the definition of the various enums and custom data types being used in the LinkedIn design:

Note: JavaScript does not support enumerations so we will be using the Object.freeze() method as an alternative that freezes an object and prevents further modifications.

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Constant definitions

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The Account class

// Person will be an abstract class
public abstract class Person {
  private String name;
  private Address address;
  private String email;
  private String phone;
  private Account account;
}
public class Admin extends Person {
  public boolean blockUser(User user);
  public boolean unblockUser(User user);
  public boolean disablePage(CompanyPage page);
  public boolean enablePage(CompanyPage page);
  public boolean deleteGroup(Group group);
}
public class User extends Person {
  private int userId;
  private Date dateOfJoining;
  private Profile profile;
  private List<User> connections;
  private List<User> followsUsers;
  private List<CompanyPage> followCompanies;
  private List<Group> joinedGroups;
  private List<CompanyPage> createdPages;
  private List<Group> createdGroups;
  public boolean sendMessage(Message message);
  public boolean sendInvite(ConnectionInvitation invite);
  public boolean cancelInvite(ConnectionInvitation invite);

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The Person, Admin, and User classes

public class Recommendation {
  private int userId;
  private Date createdOn;
  private String description;
  private boolean isAccepted;
}
public class Achievement {
  private String title;
  private Date dateAwarded;
  private String description;
}
public class Analytics {
  private int searchAppearances;
  private int profileViews;
  private int postImpressions;
  private int totalConnections;
}

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The Recommendation, Achievement, and Analytics classes

public class Experience {
  private String title;
  private String company;
  private Address location;
  private Date startDate;
  private Date endDate;
  private String description;
}
public class Education {
  private String school;
  private String degree;
  private Date startDate;
  private Date endDate;
  private String description;
}
public class Skill {
  private string name;
}
public class Profile {
  private String headline;
  private String about;
  private String gender;
  private List<byte> profilePicture;
  private List<byte> coverPhoto;
  private List<Experience> experiences;
  private List<Education> educations;
  private List<Skill> skills;

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The Experience, Education, Skill, and Profile classes

public class Job {
  private int jobId;
  private String jobTitle;
  private Date dateOfPosting;
  private String description;
  private CompanyPage company;
  private String employmentType;
  private Address location;
  private JobStatus status;
}
public class CompanyPage {
  private int pageId;
  private String name;
  private String description;
  private String type;
  private int companySize;
  private User createdBy;
  private List<Job> jobs;
  public boolean createJobPosting();
  public boolean deleteJobPosting(Job job);
}
public class Group {
  private int groupId;
  private String name;
  private String description;
  private int totalMembers;
  private List<User> members;

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The Job, CompanyPage, and Group classes

public class Post {
  private int postId;
  private User postOwner;
  private String text;
  private List<byte> media;
  private int totalReacts;
  private int totalShares;
  private List<Comment> comments;
  public boolean updateText();
}
public class Comment {
  private int commentId;
  private User commentOwner;
  private String text;
  private int totalReacts;
  private List<Comment> comments;
  public boolean updateText();
}
public class Message {
  private int messageId;
  private User sender;
  private List<User> recipients;
  private String text;
  private List<byte> media;
  public boolean addRecipients(List<User> recipients);
}

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The Post, Comment, Message, and ConnectionInvitation classes

Search, catalog, and notification#

The SearchCatalog class contains information on users, company pages, groups, and jobs. It also implements the Search interface class to enable the search functionality based on the given criteria (user, company page, group, and job keywords).

The Notification class is responsible for sending notifications to users about any new messages, comments, posts, or connection invitations via the built-in notification option.

The definition of these classes is given below:

public interface Search {
  // Interface method (does not have a body)
  public List<User> searchUser(String name);
  public List<CompanyPage> searchCompany(String name);
  public List<Group> searchGroup(String name);
  public List<Job> searchJob(String title);
}
public class SearchCatalog implements Search {
  private HashMap<String, List<User>> users;
  private HashMap<String, List<CompanyPage>> companies;
  private HashMap<String, List<Group>> groups;
  private HashMap<String, List<Job>> jobs;
  public void addNewUser(User user);
  public void addNewCompany(CompanyPage company);
  public void addNewGroup(Group group);
  public void addNewJob(Job job);
  public List<User> searchUser(String name) {
    // functionality
  }
  public List<CompanyPage> searchCompany(String name) {
    // functionality
  }
  public List<Job> searchJobs(String title) {
    // functionality
  }

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The Search interface and the SearchCatalog and Notification classes

LinkedIn classes#

Constants#

Account#

Person, admin, and user#

Recommendation, achievement, and analytics#

Profile, experience, education, and skill#

Company, job, and group#