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Start your free trialKemish Alejandro Grajeda
923 PointsMismatch from String to Collection
There is a problem in line 19 of the Blog class, the posts can't be added to the allAuthors Set. What is causing this problem?
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.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 List<BlogPost> getPosts() {
return mPosts;
}
public Set<String> getAllAuthors(){
Set<String> allAuthors = new TreeSet<String>();
for (BlogPost posts: mPosts){
allAuthors.addAll(posts.getAuthor());
}
return allAuthors;
}
// String cannot be converted to Collection
}
1 Answer
Kevin Faust
15,353 PointsHi Kemish,
on this line:
allAuthors.addAll(posts.getAuthor());
it should be .add and not .addAll. the reason is because everytime we loop, we only take one blogpost object from our mPosts list and put into the set. addAll is used if you want to put something with many things inside it such as if you want to add an entire array of several things to a set.
Kemish Alejandro Grajeda
923 PointsKemish Alejandro Grajeda
923 PointsThanks Kevin it makes sense