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Start your free trialRogelio Valdez
6,244 PointsHelp
Help!! I don't think I really understood the task for the challenge so I am messing my code up and rewriting it over and over again and now it's a complete mess!! I am getting all kinds of compile error and even if it didn't had them The program will still not do what it should since I'm not understanding what I should do.
Can any one help me out with what the taks is for this challenge? In Blog.java add a new method called getCategoryCounts. It should return a Map of category to count calculated by looping over all the posts.
P.S. Please don't spoil the answer I want to get there my self. Thanks.
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;
}
}
package com.example;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
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;
}
public Map<String, List<BlogPost>> getCategoryCounts() {
Map<String, List<BlogPost>> postsByCategory = new HashMap<String, List<BlogPost>>();
for (BlogPost myPost : mPosts) {
postsByCategory = categoryCounts.getCategory());
if (postsByCategory == null) {
postsByCategory = new ArrayList<BlogPost>();
categoryCounts.put(categoryCounts.getCategory(), postsByCategory);
}
postsByCategory.add(categoryCounts);
}
return categoryCounts;
}
}
2 Answers
Seth Kroger
56,413 PointsThe challenge is asking for how many posts are in a category, not for the list of them. So you should be returning a Map<String, Integer>.
Rogelio Valdez
6,244 PointsSo that takes me a little closer.. I hope.
I am still getting something wrong since I am not understanding the for loops for this exercise (I did understood the use of them in the lesson or I least I think I did). I am making a public method, that returns a Map in the form String,Int called CategoryCounts receives no arguments. I created a new HashMap named categoryCounts. Then I have a type Blogpost for the variable blog. I should then get a String that is the categories(one at a time) and store them in categoryCounts and add to the counts if they are repeated.
If I submit my code like this I get this error:
./com/example/Blog.java:33: error: cannot find symbol
for (String categories : blog.getPosts()) {
^
symbol: method getPosts()
location: variable blog of type BlogPost
Note: JavaTester.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error
public Map<String, Integer> getCategoryCounts() {
Map<String, Integer> categoryCounts = new HashMap<String, Integer>();
for (BlogPost blog : mPosts) {
for (String categories : blog.getPosts()) {
Integer count = categoryCounts.get(categories);
if (count == null) {
count = 0;
}
count++;
categoryCounts.put(categories, count);
}
return categoryCounts;
}
Rogelio Valdez
6,244 PointsRogelio Valdez
6,244 PointsThank you! This helps a lot since I had no idea what the exercise is asking. I am still having some trouble with the for loops. Could you help me out? (not giving me the answer)