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Java Java Objects Delivering the MVP Forum

I'm stuck!! please help.

I'm stuck could somebody help me?

Forum.java
public class Forum {
  private String topic;

  public Forum(String topic) {
    topic = topic;
  }

  public String getTopic() {
      return topic;
  }

  public void addPost(ForumPost post) {
      System.out.printf("New post from %s %s about %s.\n",
                         post.getAuthor().getFirstName(),
                         post.getAuthor().getLastName(),
                         post.getTitle());

  }
}
User.java
public class User {
  private String firstName;
  private String lastName;

  public User(String firstName, String lastName) {
    // TODO:  Set the private fields here
    firstName = firstName;
    lastName = lastName;
  }

  public String getFirstName() {
    return firstName;
  }

  public String getLastName() {
    return lastName;
  }
}
ForumPost.java
public class ForumPost {
  private User author;
  private String title;
  private String description;

  public ForumPost(User author, String title, String description) {
    this.author = author; 
    this.title = title; 
    this.description = description;
  }

  public User getAuthor() {
    return author;
  }

  public String getTitle() {
    return title;
  }

  public String getDescription() {
    return description;
  }

}
Main.java
public class Main {

  public static void main(String[] args) {
    System.out.println("Beginning forum example");
    if (args.length < 2) {
      System.out.println("Usage: java Main <first name> <last name>");
      System.err.println("<first name> and <last name> are required");
      System.exit(1);
    }

    Forum forum = new Forum("Java");
    String firstName = args[0];
    String lastName = args[1];
    User author = new User(firstName, lastName);
    ForumPost post = new ForumPost(author, "title", "description");
    forum.addPost(post);
  }
}

1 Answer

Your constructors in both the Forum and User classes are incorrect. You need to use the "this" keyword before the instance variable name to distinguish it from the parameter name.

Like so

public User(String firstName, String lastName) {
    // TODO:  Set the private fields here
    this.firstName = firstName;
    this.lastName = lastName;
  }

public Forum(String topic) {
    this.topic = topic;
  }

Hi Ted,

thanks, i've made my changes but i'm still getting the error:

Bummer! Are you sure you used the arguments passed in from the main method in Main.java? args[0] is the firstName and args[1] should be the last name