NullPointerException error for task 4 of 4, wrapping up

Question

Been stuck on this exercise for a while and couldn't find the answer in the forums. Keep getting the error = Bummer! java.lang.NullPointerException (Look around Forum.java line 14). No clue what to do here, any help would be appreciated, thanks.
```ForumPost.java
public class ForumPost {
  private User mAuthor;
  private String mTitle;
  private String mDescription;
  public ForumPost(User author, String title, String description){
    author = mAuthor;
    title = mTitle;
    description = mDescription;
  }
  public String getDescription(){
    return mDescription;
  }
  public User getAuthor() {
    return mAuthor;
  }
  public String getTitle() {
    return mTitle;
  }
  // TODO: We need to expose the description
}
```
```User.java
public class User {
  private String mFirstName;
  private String mLastName;
  public User(String firstName, String lastName) {
    mFirstName = firstName;
    mLastName = lastName;
  }
  public String getLastName(){
    return mLastName;
  }
  public String getFirstName(){
    return mFirstName;
  }
}
```
```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.
",
                         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, "Title", "Description");
    forum.addPost(post);
  }
}
```

Benjamin Larson · Accepted Answer

Hi Sonam, 
It's actually Step 3 where you made the error, even though the Challenge let it pass. Within the ForumPost constructor, you swapped the member assignments with the parameters values. It should look like this:
java
  public ForumPost(User author, String title, String description){
    mAuthor = author;
    mTitle = title;
    mDescription = description;
  }

Simple mistakes are the most frustrating :D

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Sonam Klein

Sonam Klein

NullPointerException error for task 4 of 4, wrapping up

1 Answer

Benjamin Larson

Benjamin Larson

Sonam Klein

Sonam Klein