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

Olha Markova
Olha Markova
2,050 Points

I get multiple errors

While trying to solve the challenge I get multiple errors. What is wrong with my code?

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.Set;
import java.util.TreeSet;
import java.util.Map;
import java.util.HashMap;

import com.example.BlogPost;

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> categoryCounts = new HashMap <String, Integer>();
  for (BlogPost post : mPosts){
  for (String category : post.getCategoryCounts()){
  Integer count = categoryCounts.get(category);
    if (count == null){
    count = 0;
    }
    count ++;
    categoryCounts.put(category, count);
    }
  }
  System.out.printf("Category  counts: %s, %n", categoryCounts); 
}

1 Answer

Wout Ceulemans
Wout Ceulemans
17,603 Points

Reference: https://hastebin.com/oxaqikobup.swift

In your Blog class, starting from line 29 everything is directly put into the class. While declaring a variable there might be legal, the other statements are not (like the for loops at lines 30 & 31, their bodies and that last System.out.printf statement)

Richard Lambert
Richard Lambert
Courses Plus Student 7,180 Points

Wout Ceulemans is spot on. The code you've written appears to be correct, but you need to place this within a method getCategoryCounts(), which returns a value of type Map<String, Integer>. There is no requirement to print a formatted string to stdout.

Hope this helps