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Start your free trialJohn Harles
20,614 PointsJava data structures challenge after the Set lesson, have compile errror.
The challenge question is: I've added a new class called Blog. It is initialized with a list of BlogPost objects. Create a method in the Blog class called getAllAuthors that loops over all the posts and returns a java.util.Set of all the authors, which are stored as strings. They should be sorted alphabetically.
The error I'm getting is ./com/example/Blog.java:20: error: cannot find symbol Set authors = new TreeSet(); ^ symbol: class string location: class Blog Note: JavaTester.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 1 error
The suggestion is I haven't included the necessary import statement. I believe I included all the necessary import statements.
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.*;
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<string>();
for(BlogPost post : mPosts){
authors.add(post.getAuthor());
}
return authors;
}
}
1 Answer
Kourosh Raeen
23,733 PointsString should be capitalized:
Set<String> authors = new TreeSet<String>();
John Harles
20,614 PointsJohn Harles
20,614 PointsThanks for pointing out that I didn't capitalize the s in String. That solved the problem and it works.
Thanks for you help. John
Kourosh Raeen
23,733 PointsKourosh Raeen
23,733 PointsGlad I could help! Happy coding!