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Java Java Objects (Retired) Delivering the MVP Wrapping up

Diego Marrs
Diego Marrs
8,243 Points

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
23,732 Points

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

Diego Marrs
Diego Marrs
8,243 Points

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