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Java Java Objects Delivering the MVP Forum

Steven Morimoto
Steven Morimoto
Courses Plus Student 1,836 Points

Can someone please help me....again?

On line 17 of the Main class, I understand that in the parameter of new ForumPost you have to have all that is in the parameters in the ForumPost class. However, I seem to be unable to correctly enter in the first argument due to it being a User data type instead of a String like the other two. I understand that somehow you have to link User author with firstName and lastName but I'm really stuck as to how to do that. Also, I was wondering why author is a User variable instead of making it another String variable?

public class Forum {
  private String topic;

  // TODO: add a constructor that accepts a topic and sets the private field topic
  public Forum(String topic)
    this.topic = topic;
  public String getTopic() {
    return topic;

  // Uncomment this when you are prompted to do so
  public void addPost(ForumPost post) {   //ForumPost is author, title, and description from ForumPost
    System.out.printf("A new post in %s topic from %s %s about %s is available",

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
    this.firstName = firstName;
    this.lastName = lastName;

  public String getFirstName()
    return firstName;

  public String getLastName()
    return lastName;

  // TODO: add getters for firstName and lastName

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() {
    //author = getFirstName().getLastName();
    return author;

  public String getTitle() {
    return title;

  public String getDescription() {
    return description;
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");
    //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.getAuthor(), args[1], args[2]);   //ForumPost line 16

// */


2 Answers

Hi Steven,

The ForumPost class constructor takes a User object (you have one called author), and two strings.

So, pass in the User instance called author - no need to call a method on it, the class is expecting the object. Then add in two strings. be imaginative, so something like "A Title" and "A description" will work just fine!

That gives you:

ForumPost post = new ForumPost(author, "A title", "A description"); 

I hope that makes sense.


No problem! I hope the reasoning was clear. The link between a User object and its firstName and lastName is handled internally. The ForumPost object doesn't need to know about that; it is just expecting to see a User-sized object being received. It'll worry about its contents later.