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Start your free trialSonam Klein
858 PointsNullPointerException error for task 4 of 4, wrapping up
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.
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
}
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;
}
}
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());
}
}
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);
}
}
1 Answer
Benjamin Larson
34,055 PointsHi 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:
public ForumPost(User author, String title, String description){
mAuthor = author;
mTitle = title;
mDescription = description;
}
Simple mistakes are the most frustrating :D
Sonam Klein
858 PointsSonam Klein
858 PointsAh great, i had a feeling it was something from one of the previous challenges. thanks for the help!