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Java Java Objects Delivering the MVP Forum

Posted by Timothy Hilley
Timothy Hilley
2,292 Points

I dont get why this isnt working. keeps asking if im sure ive used the arguments in main right for the user class

"x Bummer! are you sure you used to arguments in main (args[]), first name args[0] and last name is args[1].

which i did. so.. idk.

Forum.java 
public class Forum {
  private String topic;

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

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

  public String getTopic() {
    return topic;
  }



  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 = "";
    lastName = "";

  }
  public String getFirstName() {
    return firstName;
  }
  public String getLastName() {
    return lastName;
  }

  // TODO: add getters for firstName and 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;
    title = "";
    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");
    // 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, "Java", "how to code");
    forum.addPost(post);


  }

}

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

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

Take the ForumPost constructor:

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

You correctly assign the author field variable but you incorrectly assign the title and description. You are just setting the parameters passed in to empty strings which is not what you are meant to do.

The title and description should be assigned in exactly the same way as the author is. Like this:

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

If you fix that issue in both the User and ForumPost class constructors then your code will work.

Timothy Hilley
Timothy Hilley
2,292 Points

I corrected (ty btw this would have been an issue later):

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

but still same error occurs. " 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

Timothy Hilley
Timothy Hilley
2,292 Points

aaaand then i fixed the constructor in user. thanks so much :D