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

Tarvinder Kalra
Tarvinder Kalra
4,081 Points
Posted by Tarvinder Kalra
Tarvinder Kalra
4,081 Points

Maps (JDS) challenge, I get bummer that expected 1 , received 1. Whats that for?

I am working on Maps challenge and challenge is to return maps of category of blogs and its count. When i check the code, bummer says for category Entertainment, expected 1, received 1. If both are same why there is bummer. I am not sure what to correct. Please help

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.Map;
import java.util.HashMap;
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<>();
    for (BlogPost post: mPosts) {
      authors.add(post.getAuthor());
    }
    return authors;
  }

    public Map<String, Integer> getCategoryCounts(){
         Map<String, Integer> catCounts = new HashMap<String, Integer>();
          int count = 0;
         for(BlogPost blogs : mPosts){
               String category = blogs.getCategory();
             if(catCounts.get(category) == null )
               count = 1;
              else count = (catCounts.get(category)).intValue() + 1;

         System.out.println(category + "," + count);
         catCounts.put(category, new Integer(count));
    }
    return catCounts;
  }
}

2 Answers

Grigorij Schleifer
Grigorij Schleifer
10,365 Points
Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Hi Tarvinder,

you are almost done and your logic is good:

 public Map<String, Integer> getCategoryCounts(){
         Map<String, Integer> catCounts = new HashMap<String, Integer>();
         for(BlogPost blogs : mPosts){
               String category = blogs.getCategory();
               // for every BlogPost get the category
               Integer count = catCounts.get(category);
              // proof if there is this category inside the Map

             if(count == null) {
               count = 0; // changed to zero
           // if no category is in the Map -> count is null
           // set count to 0
         } // close the loop
              count++;
        // and increment the count if category is in the Map
        // System.out.println(category + "," + count);
        // you dont need to print something here
         catCounts.put(category, count);
        // no need to create an extra Integer object
        // just add count
    }
    return catCounts;
  }
}

Let me know if this was helpful or not ...

Grigorij

Tarvinder Kalra
Tarvinder Kalra
4,081 Points
Tarvinder Kalra
Tarvinder Kalra
4,081 Points

Thanks Grigorji, it solved the problem by just erasing - new Integer(count), though I could not understand what the problem was :)

Stewart Rap
Stewart Rap
8,167 Points
Stewart Rap
Stewart Rap
8,167 Points

I had the same error and also had to remove a "new Integer()"..

Is this is a bug in the exercise?