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Java Java Objects (Retired) Delivering the MVP Wrapping up

the User author element reeeally giving me trouble at the end of this challenge

I'm so close to wrapping up this challenge but I get a "nullPointerException" error. I don't know how to remedy this. It's the last part, I think I have it right, I'm not sure how I've messed up.

Any help would be appreciated.

thank you

public class ForumPost {
  private User mAuthor;
  private String mTitle;
  private String mDescription;

  public ForumPost(User author, String title, String description)
    User mAuthor = author;
    mTitle = title;
    mDescription = description;

  public String getDescription()
    return mDescription;

  public User getAuthor() {
    return mAuthor;

  public String getTitle() {
    return mTitle;

  // TODO: We need to expose the description
public class User {

  private String mFirstName;
  private String mLastName;

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

  public String getFirstName()
    return mFirstName; 

  public String getLastName()
    return mLastName; 

public class Forum {
  private String mTopic;

  public Forum(String topic)
    mTopic = topic;

  public String getTopic() {
      return mTopic;

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

public class Example {

  public static void main(String[] args) {
    System.out.println("Starting forum example...");
    if (args.length < 2) {
       System.out.println("first and last name are required. eg:  java Example Craig Dennis");
    Forum forum = new Forum("Java");
    // Take the first two elements passed args
    User author = new User("Dax", "Stucki");
    // Add the author, title and description
    ForumPost post = new ForumPost(author, "Done", "Woo Hoo");

1 Answer

Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Hi Dax,

you should use the command line arguments for the creation of the User object like this:

 User author = new User(args[0], args[1]);

So the compiler takes this arguments for the creation of the User object.