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

Carlo Antonio Bilbao
Carlo Antonio Bilbao
24,113 Points

Java, Set Challenge

I feel like the code looks ok. But getting an error that i might not have imported the correct util. Any suggestions?

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

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;


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;
  }
}
com/example/Blog.java
package com.example;

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

public class Blog {
  List<BlogPost> mPosts;

  public Set<String> getAllAuthors() {
    Set<String> allAuthors = new TreeSet<String>();
    for (BlogPost blogPost : mPosts) {
     allAuthors.addAll(blogPost.getAuthor()); 
    }
    return allAuthors;
  }

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

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

1 Answer

Alexandra Barnett
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Alexandra Barnett
Front End Web Development Techdegree Graduate 46,473 Points

Hi Carlo!

The imports are good, rather than addAll to the Set, just add instead. As you are looping over, you are adding one author at a time:

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