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Java Java Objects (Retired) Delivering the MVP Wrapping up

I'm there!...almost...

So i'm trying to run the final challenge for 'Java Objects' (With everything un-commented and my title and description inserted), when I run my program...this error pops up:

Starting forum example...
java.lang.NullPointerException
    at Forum.addPost(Forum.java:14)
    at Example.main(Example.java:13)
    at JavaTester.run(JavaTester.java:183)
    at JavaTester.main(JavaTester.java:43)

Help is appreciated!

Also, my entire code:

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

  public User getAuthor() {
    return mAuthor;
  }

  public String getTitle() {
    return mTitle;
  }

  public String getDescription() {
    return mDescription;
  }

  public ForumPost(User author, String title, String Description) {
  }
}
User.java
public class User {
  private String mFirstName;
  private String mLastName;

  public User(String firstName, String lastName) {
    mFirstName = firstName;
    mLastName = lastName;
  }

  public String getFirstName() {
    return mFirstName;
  }

  public String getLastName() {
    return mLastName;
  }
}
Forum.java
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",
                         post.getAuthor().getFirstName(),
                         post.getAuthor().getLastName(),
                         post.getTitle());
  }
}
Example.java
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(args[0], args[1]);
    // Add the author, title and description
    ForumPost post = new ForumPost(author, "I did it!", "Whoooo!");
    forum.addPost(post);
  }
}

1 Answer

Kourosh Raeen
Kourosh Raeen
23,733 Points

Hi Diego - Your ForumPost constructor's body is empty. You need to initialize the member fields in there.

Ah! I knew there was something up with that constructor...Thanks alot! :)