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Java Java Objects Delivering the MVP Forum

jag
jag
18,266 Points

What am I not seeing?

Step 1-3 pass but for the final it's saying if I'm sure I'm adding the correct args for user.

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;
  }
  /* Uncomment this when you are prompted to do so*/
  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);
    }
    /* Uncomment this when prompted */
    Forum forum = new Forum("Java");
    // TODO: pass in the first name and last name that are in the args parameter
    User author = new User("John","Doe");
    // TODO: initialize the forum post with the user created above and a title and description of your choice
    ForumPost post = new ForumPost(author, "Book", "About a book");
    forum.addPost(post);
  }

}

2 Answers

Hi there,

I think you should be seeing an error referring to using the arguments passed in for firstName and lastName. To do this, access firstName as args[0] and lastName as args[1]. So your User creation looks like:

User author = new User(args[0], args[1]);

Let me know how you get on.

Steve.

I just want to elaborate, because this challenge made me quit treehouse when I first started. And I see it asked very frequently in the forums.

Up until this point, you have largely ignored the main method. In one video he briefly explained how the main method works, but he never used it for anything. In this challenge, you are using it.

Here is the main method:

public static void main(String[] args) {

As you know by now, 'main' is a method that has 1 parameter named 'args'. This parameter 'args' happens to be a String array. Knowing this will help explain the task.

// TODO: pass in the first name and last name that are in the args parameter

When you read 'parameter' in that sentence you should instantly think somewhere in a method signature. More specifically, in the 'args parameter'. So then you scroll through your code line-by-line to find a method with a parameter named 'args'.

Since the first and last name are stored there, you have to assume the first name is the first index while the second name is the second index.

That is fair comment, Philip. The use of the passed-in args[] isn't hugely clear. Or at least it wasn't in the retired course that I did; I haven't taken the newly-released one. But, it is good to have a challenge fro time to time, I guess! :wink: :+1:

Steve.

jag
jag
18,266 Points

Thanks Steve & Philip for the elaboration. I get it now but I was rather confused at first knowing I was missing something.

No problem, Jag! :+1: :smile:

Happy to help.

Steve.