Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Objects Delivering the MVP Forum

Albert González
Albert González
22,953 Points

What's my 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

I don't see the error!

Forum.java
public class Forum {
  private String topic;

  // TODO: add a constructor that accepts a topic and sets the private field topic

  public String getTopic() {
    return topic;
  }

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


  /* Uncomment this when you are prompted to do so*/
  public void addPost(ForumPost post) {
    System.out.printf("A new post in %s topic from %s %s about %s is available",
            topic,
            post.getAuthor().getFirstName(),
            post.getAuthor().getLastName(),
            post.getTitle()
    );
  }


}
User.java
public class User {
  // TODO: add private fields for firstName and lastName

  private String firstName;
  private String lastName;

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



  // TODO: add getters for firstName and lastName
  public void setFirstName(String firstName)
        {
                this.firstName = firstName;
        }

  public String getFirstName()
        {
                return firstName;
        }

  public void setLastName(String LastName)
        {
                this.lastName = lastName;
        }

  public String getLastName()
        {
                return lastName;
        }


}
ForumPost.java
public class ForumPost {
  private User author;
  private String title;
  private String description;

  // TODO: add a constructor that accepts the author, title and 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);
    }
    // Uncomment this when prompted
    Forum forum = new Forum("Java");
    // TODO: pass in the first name and last name that are in the args parameter
    User author = new User(args[0], args[1]);
    // TODO: initialize the forum post with the user created above and a title and description of your choice
    ForumPost post = new ForumPost(author, "Title", "Description");
    forum.addPost(post);

// 
  }

}

1 Answer

andren
andren
28,558 Points

The issue is the constructors you wrote for the Forum and User class.

Take the Forum constructor:

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

You set the parameter topic to the field variable topic, but you are meant to do the exact opposite. Like this:

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

The same issue is present in the User constructor with the firstName and lastName assignments.

If you fix the issues in both the Forum and User constructors then your code should work.