Understanding the args parameter/initialization

Question

In the TODO notes in the class Main, it's asking me to "pass in the first name and last name that are in the args parameter" and to "initialize the forum post with the user created above and a title and description of your choice".

I'm honestly lost as to what it's asking me to do. How do I tell what's in the args parameter? What syntax would be used to initialize the forum post correctly?

Forum.java

public class Forum {
  private String 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 {
  private String firstName;
  private String lastName;

  public User(String firstName, String lastName) {
    this.firstName = firstName;
    this.lastName = 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;

  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
    User author = new User();
    // TODO: initialize the forum post with the user created above and a title and description of your choice
    ForumPost post = new ForumPost();
    forum.addPost(post);


  }

}

Answer 1 · 2017-05-23T21:47:59Z

May 23, 2017 9:47pm

Hi there,

This part of the challenge causes many people a problem! It could probably be made clearer but, hey, we all like a challenge!

The Java program is centred around a main method. You can see that in the Main class. This method takes an array of strings as a parameter. This array is called args and is of type String[] so it is an array. When the app is started the firstName and lastName are passed in as arguments (args) to the main method. They are the only two, and so the first, elements of the args array. So, firstName is held in args[0] and lastName is in args[1].

So, to create the User instance, pass those in as the arguments for the constructor:

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

That should let you get to the ForumPost` constructor.

Let me know how you get on.

Steve.

Welcome to the Treehouse Community

Looking to learn something new?

Kaytlynn Ransom

Kaytlynn Ransom

Understanding the args parameter/initialization

1 Answer

Steve Hunter

Steve Hunter