Maps Challenge

Question

When I run 'Check Work' it tells me I'm returning the wrong count for food, 'expected 2, received 3'. However, I've rewritten the code out in full externally with my own tests and I can't recreate the problem. Any clues are most welcome.

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;
  }
}

Blog.java

package com.example;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
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 Map<String, Integer> getCategoryCounts() {
    Map<String, Integer> categoryCounts = new HashMap<>();
    Integer count = 0;

    for (BlogPost post: mPosts) {
      String category = post.getCategory();

      // Check if the category is new
      if (!categoryCounts.containsKey(category)) {
        count = 0;
      }
      count++;
      categoryCounts.put(category, count);
    }
    return categoryCounts;
  }

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

Answer 1 · 2015-06-11T14:57:18Z

June 11, 2015 2:57pm

Hmmm...what if that count variable was inside the for loop? Seems to be ever incrementing and not resetting. In fact, what if you got it out of the Map each time by key. Remember if a key doesn't exist you will get back a null value.

That help? (I can be less hinty if you want me to be) ;)

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Iain Diamond

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Maps Challenge

1 Answer

Craig Dennis

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Iain Diamond

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Iain Diamond

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Craig Dennis

Craig Dennis