Set vs SortedSet

Question

Why would it be best practice to use Set in this case, instead of SortedSet? Based on the work we did in the repl leading up to this, it would seem that SortedSet is the better choice, as it will enable methods like headSet and tailSet.

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.SortedSet;
import java.util.TreeSet;

public class Blog {
  List<BlogPost> mPosts;

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

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

  public SortedSet<String> getAllAuthors() {
    SortedSet<String> authors = new TreeSet<String>();
    for (BlogPost post : mPosts) {
      authors.add(post.getAuthor());
    }
    return authors;
  }
}

Answer 1 · 2015-07-09T17:42:45Z

July 9, 2015 5:42pm

Good point!

I specifically asked for a Set though. It all depends on how you plan to use the Set. Since I wasn't going to use those that way, I decided to go to the more open Set interface.

Make sense?

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Dan Stoppelman

Dan Stoppelman

Set vs SortedSet

1 Answer

Craig Dennis

Craig Dennis