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Start your free trialRonald Greer
Front End Web Development Techdegree Graduate 56,430 Pointsi need help with task 4 of 4 with forum.
please help
public class Forum {
private String topic;
private String firstName;
private String lastName;
public String getTopic() {
return topic;
}
public Forum(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.\n",
topic,
post.getAuthor().getFirstName(),
post.getAuthor().getLastName(),
post.getTitle());
}
}
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.firstName = lastName;
}
// TODO: add getters for firstName and lastName
public String getFirstName() {
return this.firstName;
}
public String getLastName() {
return this.lastName;
}
}
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;
}
}
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 of the damn thing", "About some jibberish like C++");
forum.addPost(post);
}
}
2 Answers
Long Nguyen
10,007 PointsThe constructor in the User.java file initializes the firstName variable twice. That could be the problem.
public User(String firstName, String lastName) {
// TODO: set and add the private fields
this.firstName = firstName;
this.firstName = lastName;
}
Brian Bochicchio
19,978 PointsHere's what I found (short answer)
Look at your variable assignments in User.java
public User(String firstName, String lastName) {
// TODO: set and add the private fields
this.firstName = firstName;
this.firstName = lastName;
firstName is being first being assigned the value of firstName (Bob) and then the value of lastName(McBobberson ).
Because lastName is never assigned a value, the author's name ends up being "McBobberson" null instead of "Bob" "Mc Bobberson"
Which explains why the preview output showed...
A new post in Java topic from McBobberson null about title of the damn thing is available
... when I first ran your code in the challenge.
Once that was fixed, the code passed the challenge.
I'll be completely honest this didn't jump out at me right away like it should have. If you are interested in how I figured it out using strategically placed System.out.println commands read on.
I started by figuring out what values I should be expecting by printing the args to the preview:
Main.java
public static void main(String[] args) {
System.out.println("Beginning forum example:");
System.out.println("Arg Values: " + args[0] + ":" + args[1]);
Beginning forum example:
Bob:McBobberson
Then made sure those were the values being passed into User.java
User.java
public User(String firstName, String lastName) {
// TODO: set and add the private fields
this.firstName = firstName;
this.lastName = lastName;
System.out.println("Author Created: " + firstName + ":" + lastName);
}
Author Created: Bob:McBobberson
The variables being passed in from args[0] and args[1] are correct . So far so good.
On to the next place we reference the author
ForumPost.java
public ForumPost(User author, String title, String description) {
this.author = author;
this.title = title;
this.description = description;
System.out.println("Post Created: " + author.getFirstName() + ":" + author.getLastName());
Post Created: McBobberson: null
Umm.... that's not right. We passed in the right values. So something is going wrong when the User is being created. Looking more closely at User.java I saw that firstName is being first being assigned the value of firstName (Bob) and then the value of lastName(McBobberson ). Also that lastName is never getting assigned a value.
Brian DuPont
30,448 PointsBrian DuPont
30,448 PointsI haven't tested, but just read through the code, and noticed in ForumPost.java that your getters are returning author, title, description without the 'this' key word. They should return this.author, this.title, this.description. Hope that fixes it.