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Java Java Data Structures Exploring the Java Collection Framework Sets

Gonzalo Torres del Fierro
PLUS
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points
Posted by Gonzalo Torres del Fierro
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points

Set Challenge

hello, i was reading the forum coments, and serching for my self, but i can not go throw this unique_error, that is telling me this;

./com/example/Blog.java:18: error: cannot find symbol for (BlogPosts authorName : mPosts) { ^ symbol: class BlogPosts location: class Blog Note: JavaTester.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 1 error

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 com.example.BlogPost;


public class Blog {
  List<BlogPost> mPosts;

  public Blog(List<BlogPost> posts) {
    mPosts = posts;
  }

 public Set <String> getAllAuthors(){
   Set<String> set = new TreeSet<String>();
   for (BlogPosts authorName : mPosts) { 
     set.add(authorName.getAuthor());
   }
   return set;
 }
  public List<BlogPost> getPosts() {
    return mPosts;
  }
}

2 Answers

Gonzalo Torres del Fierro
PLUS
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points
Gonzalo Torres del Fierro
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points

hello, i found finally, the error, was related with this:

1-. first, i had to import the proper interface to my programming place , and here we have what was necessary to do it; package com.example;

import java.util.List; import java.util.Set; import java.util.TreeSet; import java.util.HashSet; import com.example.BlogPost;

2-. then, i realize, that it was an extra "S" on my Code, and i just deleted... ( see below ,for (BlogPosts.../ must say "BlogPost")

public Set <String> getAllAuthors(){ Set<String> set = new TreeSet<String>(); for (BlogPosts authorName : mPosts) { set.add(authorName.getAuthor()); }

and with this two litle changes, everything was running ok...

Jeremy Hill
Jeremy Hill
29,567 Points
Jeremy Hill
Jeremy Hill
29,567 Points

There probably shouldn't be a space between: "Set" and <String> in you method heading. This is what I did to pass the challenge:

package com.example;

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;
  }
}
Gonzalo Torres del Fierro
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points
Gonzalo Torres del Fierro
Gonzalo Torres del Fierro
Courses Plus Student 16,751 Points

Jeremy, thank you , for your answer, and i´m glad to have persons like you that really help on this task of learning code...