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Java Java Objects (Retired) Delivering the MVP Wrapping up

Ranjen Naidu
Ranjen Naidu
2,474 Points

Compile error for Wrapping Challenge

I am receiving the error below : Can anyone guide why this happen and how to fix it?

./Example.java:10: error: constructor User in class User cannot be applied to given types; User author = new User(); ^ required: String,String found: no arguments reason: actual and formal argument lists differ in length ./Example.java:12: error: constructor ForumPost in class ForumPost cannot be applied to given types; ForumPost post = new ForumPost(); ^ required: User,String,String found: no arguments reason: actual and formal argument lists differ in length 2 errors

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

  public ForumPost(User author , String title , String description){
  mAuthor = author;
  mTitle = title;
  mDescription = description;

  public User getAuthor() {
    return mAuthor;

  public String getTitle() {
    return mTitle;

  public String getDescription() {
    return mDescription;

  // 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 getFirstName(){
  return mFirstName;

  public String getLastName(){
  return mLastName;

public class Forum {
  private String mTopic;

  public Forum(String topic){
  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",

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();

2 Answers

Mikael Enarsson
Mikael Enarsson
7,056 Points

The error occurs because the user() constructor requires 2 arguments, a first name and a last name. You have to use two Strings when calling the constructor, i.e. User user = new User("SomeName", "SomeOtherName");.

It's pretty much the same problem with the ForumPost() constructor, but try to solve that one yourself ^^

Were you able to complete the code challenge? If not, what other questions do you have? I am happy to help!