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

Karel Schwab
Karel Schwab
12,955 Points
Posted by Karel Schwab
Karel Schwab
12,955 Points

How do you get the values of all the authors from the BlogPost list?

This is how far I got...

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.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> authors = new TreeSet<String>();
    for(String author : ) {
      authors.add(author);
    }
    return authors;
  }
}
Lukasz Walczak
Lukasz Walczak
6,620 Points
Lukasz Walczak
Lukasz Walczak
6,620 Points

Hi there!

In the needed method you should:

Loop over all the posts.

  • so data type that it looped over should be of BlogPost type (you've got String there)
  • in Blog class there is a method that returns a list of all posts, that you need to go through with each iteration

After each iteration it should add author's name to the authors string set

  • authors.add( method that gets the author from the post - it is in the BlogPost class).

Hope it helps. If you got more questions, pls do not hesitate. I'm happy to help! Have a great day!