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Java Java Objects Delivering the MVP Forum

Olha Markova
Olha Markova
2,050 Points

Problem with a challange

I am trying to complete this challange and have problem with a main class in a step 3/4. unfortunatelly I don´t know where is my mistake

Forum.java
public class Forum {
  private String topic;

  // TODO: add a constructor that accepts a topic and sets the private field topic

  public Forum (String topic){
  this.topic = topic;
  }

  public String getTopic() {
    return topic;
  }



  public void addPost(ForumPost post) {
    System.out.printf("A new post in %s topic from %s %s about %s is available",
            topic,
            post.getAuthor().getFirstName(),
            post.getAuthor().getLastName(),
            post.getTitle()
    );
  }


}
User.java
public class User {
  // TODO: add private fields for firstName and lastName
  private String firstName;
  private String lastName;

  public User(String firstName, String lastName) {
    // TODO: set and add the private fields
  this.firstName = firstName;
  this.lastName = lastName;
  }

  // TODO: add getters for firstName and lastName
  public String getFirstName(){
  return firstName;
  }

  public String getLastName(){
  return lastName;
  }

}
ForumPost.java
public class ForumPost {
  private User author;
  private String title;
  private String description;

  // TODO: add a constructor that accepts the author, title and description
  public ForumPost (User author, String title, String description){
  this.author = author;
  this.title = title;
  this.description = description;
  }

  public User getAuthor() {
    return author;
  }

  public String getTitle() {
    return title;
  }

  public String getDescription() {
    return description;
  }
}
Main.java
public class Main {

  public static void main(String[] args) {
    System.out.println("Beginning forum example");
    if (args.length < 2) {
      System.out.println("Usage: java Main <first name> <last name>");
      System.err.println("<first name> and <last name> are required");
      System.exit(1);
    }

    Forum forum = new Forum("Java");
    // TODO: pass in the first name and last name that are in the args parameter
    String [] names = {"Olha Markova"};
    User author = new User(args [0]);
    // TODO: initialize the forum post with the user created above and a title and description of your choice
    ForumPost post = new ForumPost(User, title, description);
    forum.addPost(post);


  }

}

1 Answer

andren
andren
28,521 Points

There are a couple of issues:

  1. The name string array is not needed for this task. This won't produce an error but in general it's a bad idea to add code not explicitly asked for in these challenges as it tends to confuse the code checker.

  2. The User consturctor takes two strings (first name and last name), you only provide it with one. You need to provide it with a last name from the program arguments by passing in args[1].

  3. When initializing the ForumPost object post you pass in User which is not an object, but the name of a class. You are meant to pass in author which is the User object you initialized earlier in the code. You also pass in two variables that don't exist (title and description). For those arguments you are meant to just pass in a title and description in the form of a string, the string can say anything you want.

If you fix all of those issues like this:

public class Main {

  public static void main(String[] args) {
    System.out.println("Beginning forum example");
    if (args.length < 2) {
      System.out.println("Usage: java Main <first name> <last name>");
      System.err.println("<first name> and <last name> are required");
      System.exit(1);
    }

    Forum forum = new Forum("Java");
    // TODO: pass in the first name and last name that are in the args parameter
    User author = new User(args[0], args[1]);
    // TODO: initialize the forum post with the user created above and a title and description of your choice
    ForumPost post = new ForumPost(author, "title", "description");
    forum.addPost(post);


  }

}

Then your code will work fine.