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Java Java Objects Delivering the MVP Forum

isaac schwartzman
isaac schwartzman
963 Points
Posted by isaac schwartzman
isaac schwartzman
963 Points

every time I try to submit all it tells me is bummer try again

is it my code ?

Forum.java 
public class Forum {
  private String topic;

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

  public String getTopic() {
    return topic;
  }
public static Topic (String topic) {
private String topic = this.topic;
  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

  public User(String firstName, String lastName) {
    // TODO: set and add the private fields

  }
  public static Names (String firstName, String lastName) {
  private String firstName = this.firstName;
    firstName = ""; 
    private String lastName = this.lastName;
    lastName = '';
  }

public static getNames (){ 
  String lastNameIs = User(lastName);
  String firstNameIs = User(firstName);
  return lastNameIs;
  return firstNameIs;
}
  // TODO: add getters for firstName and 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 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();
    // 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);

// */
  }

}

2 Answers

Timothy Hilley
Timothy Hilley
2,292 Points
Timothy Hilley
Timothy Hilley
2,292 Points

topic = ""; needs to be private outside of the method to declare and initialize the String topic

private String topic = "";

also, if you have topc = ""; right after declaring this.topc (same variable), youre overwriting what you just put in it (the methods take in topic)

  private String topic = "";

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

  public String getTopic() {
    return topic;
  }
public static Topic (String topic) {
    this.topic = topic;   //the topic being placed in the methods(thispart) is now saved to the class's topic
}

also, you dont have to (and cant) privatize a variable inside a scope that is public.

Timothy Hilley
Timothy Hilley
2,292 Points

be sure to uncomment the blocks of code already supplied when prompted btw!

isaac schwartzman
isaac schwartzman
963 Points
isaac schwartzman
isaac schwartzman
963 Points

thanks for your post it actually cleared up my confusion of constructors, and sadly I was really unclear but my problem is the user section about the whole " In User.java, add private fields to store firstName and lastName, and initialize them in the provided constructor. Add public getters for firstName and lastName. " but still your response taught me a few things :)

Timothy Hilley
Timothy Hilley
2,292 Points

think about what you just wrote: and then press enter every now and then. thats called psuedo code:

In User.java,
     add private fields to store: 
           firstName
           lastName
// and then
  public User(String firstName, String lastName) {
    // TODO: initialize them in the provided constructor. 
}

public String getFirstName() {
Add public getters for firstName
}

and lastName.
Timothy Hilley
Timothy Hilley
2,292 Points
Timothy Hilley
Timothy Hilley
2,292 Points

and just to clear up anything on constructors: A constructor is the main attributes of the object that creates an object from the template. Look at a class as a play-dough mold, and the variables it takes in is the play-dough, creating an object (the instance). Without the constructor, instances cant be made. The class itself is not an object, but a blueprint on making that object. the instances are the objects. So in other classes, i can make as many playdough molds as i please and use them separately as seperate objects of the same class, because of the constructor. 

public class PlayDoughStar {

private String starColor;

public PlayDoughStar(String starColor) {
     this.starColor= starColor;
} 
//the rest of the class code
}

so in a different class, i want to make a play-dough star:

public class Table {
PlayDoughStar redStar = new PlaydoughStar("red");
PlayDoughStar blueStar = new PlaydoughStar("blue");
//Tables constructor here {
//}