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Java Java Data Structures - Retired Exploring the Java Collection Framework Sets

Jack Cummins
Jack Cummins
17,417 Points
Posted by Jack Cummins
Jack Cummins
17,417 Points

Need help. Don't know why I'm wrong.

I've added a new class called Blog. It is initialized with a list of BlogPost objects. Create a method in the Blog class called getAllAuthors that loops over all the posts and returns a java.util.Set of all the authors, which are stored as Strings. They should be sorted alphabetically.

Thanks! Jack

com/example/BlogPost.java 
package com.example;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Set;
import java.util.HashSet;
import java.util.TreeSet;


public class BlogPost implements Comparable<BlogPost>, Serializable {
  private String mAuthor;
  private String mTitle;
  private String mBody;
  private String mCategory;
  private Date mCreationDate;

  public BlogPost(String author, String title, String body, String category, Date creationDate) {
    mAuthor = author;
    mTitle = title;
    mBody = body;
    mCategory = category;
    mCreationDate = creationDate;
  }

  public int compareTo(BlogPost other) {
    if (equals(other)) {
      return 0;
    }
    return mCreationDate.compareTo(other.mCreationDate);
  }

  public String[] getWords() {
    return mBody.split("\\s+");
  }

  public List<String> getExternalLinks() {
    List<String> links = new ArrayList<String>();
    for (String word : getWords()) {
      if (word.startsWith("http")) {
        links.add(word);
      }
    }
    return links;
  }

  public String getAuthor() {
    return mAuthor;
  }

  public String getTitle() {
    return mTitle;
  }

  public String getBody() {
    return mBody;
  }

  public String getCategory() {
    return mCategory;
  }

  public Date getCreationDate() {
    return mCreationDate;
  }

public Set<String> getAllAuthors(){
    Set<String> authors = new TreeSet<String>();
    for (BlogPost posts: mPosts){
      authors.add(posts.getAuthor());
    }
    return authors;
  }
}
com/example/Blog.java 
package com.example;

import java.util.List;

public class Blog {
  List<BlogPost> mPosts;

  public Blog(List<BlogPost> posts) {
    mPosts = posts;
  }

  public List<BlogPost> getPosts() {
    return mPosts;
  }
}

2 Answers

Jason Thomas
Jason Thomas
12,519 Points

the method you're asked to create should be in the 'Blog' class.

Jack Cummins
Jack Cummins
17,417 Points
Jack Cummins
Jack Cummins
17,417 Points

Oh yeh. Huh. How did I get that wrong?

Gonzalo Torres del Fierro
PLUS
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points
Gonzalo Torres del Fierro
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points

import java.util.List; import java.util.Set; import java.util.TreeSet; public class Blog { List<BlogPost> mPosts;

public Blog(List<BlogPost> posts) { mPosts = posts; }

public List<BlogPost> getPosts() { return mPosts; }

public Set<String> getAllAuthors(){ Set<String> results = new TreeSet<String>(); for(BlogPost posty : mPosts){ results.add(posty.getAuthor()); } return results; }

}

Unsubscribed User
Unsubscribed User
1,321 Points

Code above formatted.

import java.util.List;
import java.util.Set;
import java.util.TreeSet;

public class Blog { List<BlogPost> mPosts;

    public Blog(List<BlogPost> posts) {
        mPosts = posts;
    }

    public List<BlogPost> getPosts() {
        return mPosts;
    }

     public Set<String> getAllAuthors() {
        Set<String> results = new TreeSet<String>();
        for (BlogPost posty : mPosts) {
        results.add(posty.getAuthor());
        }
        return results;
     }
}