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

Jessie Burton
Jessie Burton
5,198 Points

Cant reconcile errors

cannot find symbol on mPost

and dont know how to getCategory without BlogPost.getCategory())

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.HashMap;
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;
  }

  public Map<String, Integer> getCategoryCount() {
    Map<String, Integer> categoryCount = new HashMap<String, Integer>();
    for (BlogPost post : mPost) {
      String category = BlogPost.getCategory());
      Integer count = categoryCount.get(category);
        if (count == null) {
          count = 0;
        }
      count++;
    categoryCount.put(category, count);

    }
    return categoryCount;
    }  



}

2 Answers

Hello

This like looks wrong

String category = BlogPost.getCategory());

do you mean

String category = post.getCategory());

?

andren
andren
28,558 Points

Your code is pretty close to correct but there are some issues.

The BlogPost list is called mPosts not mPost (notice the s at the end). That is what causes the current error you are getting.

As for getting the categories, in your for loop you have access to the individual BlogPost objects in the list via the post variable. You can call the getCategory method on that to get access to the category of the post. Note also that you have an extra closing parenthesis in the line where you call getCategory which should not be there.