Invalid method declaration

public class ForumPost {
  private String mTopic;
  public Forum(String topic){
    // set mTopic to the topic passed in to the constructor
    mTopic = topic;
  }
  public String getTopic(){
    return mTopic;
  }
  public void addPost(ForumPost post){
    /* When all is ready uncomment this...
    System.out.printf("New post from %s %s about %s.\n", 
                      post.getAuthor().getFirstName(),
                      post.getAuthor().getLastName(),
                      post.getTitle());
   */
  }
}


  // TODO: We need to expose the description

public class User {

  public User(String firstName, String lastName) {
    // TODO:  Set the private fields here
  }
}

public class Forum {
  private String mTopic;

  public String getTopic() {
      return mTopic;
  }

  public void addPost(ForumPost post) {
      /* When all is ready uncomment this...
      System.out.printf("New post from %s %s about %s.\n",
                         post.getAuthor().getFirstName(),
                         post.getAuthor().getLastName(),
                         post.getTitle());
      */
  }
}

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();
    // Add the author, title and description
    // ForumPost post = new ForumPost();
    // forum.addPost(post);
  }
}