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

Tyler Combs
Tyler Combs
15,525 Points

Having trouble with a map here...

So in the video we watch before this challenge, Craig is seen making a map very similar to the one I have written out, but I get a compile error saying that basically my for-each loops have to be in a method/constructor, but Craig's syntax looks the same to me! What is going wrong here? How else could I make a "method" that returns a map?

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.HashMap;
import java.util.HashSet;
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 Set<String> getAllAuthors() {
    Set<String> authors = new TreeSet<>();
    for (BlogPost post: mPosts) {
      authors.add(post.getAuthor());
    }
    return authors;
  }

  Map<String, Integer> getCategoryCounts = new HashMap<String, Integer>();
    Set<String> categories = new HashSet<String>();
    int count;
    for (BlogPost post : mPosts) {
      categories.add(post.getCategory());
    }
    for (String category : categories) {
      if (category == null) {
        count = 0; 
      }
      count++;
      getCategoryCounts().put(category, count);
    }
}

1 Answer

Alexander Nikiforov
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Alexander Nikiforov
Java Web Development Techdegree Graduate 22,175 Points

Your solution has numbers of problems...

I can help you solve compiling errors, but that will not solve the challenge, which means you have to change the logic.

This question is so popular, I'd suggest you check the community answers by clicking "Map" at top this page, above title of your question:

Java -> Java ->Data ->Structures ->Exploring the Java Collection Framework ->Maps

Here is the direct link, if you feel troubled:

https://teamtreehouse.com/community/code-challenge:7802

Let me list you my favorite ones from there

These ones is the most descriptive, I like it, upvoted :)

https://teamtreehouse.com/community/how-do-i-solve-this-2

https://teamtreehouse.com/community/why-am-i-getting-this-error-5

And there are numbers more :)

https://teamtreehouse.com/community/need-help-106

https://teamtreehouse.com/community/stuck-in-map-java

https://teamtreehouse.com/community/im-not-sure-how-to-finish-the-getcatagorycount-method

Tyler Combs
Tyler Combs
15,525 Points

Thanks, Alexander. I actually thought that i was the only one having problems with this challenge because there were no questions linked to the video. Next time I'll actually search the community beforehand. Thank you.