Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Java Java Data Structures Organizing Data Comparable

Can someone explain what is wrong with my code or what's missing in java data structures order dates task.

These are the errors I keep getting, not sure what is expected.

./com/example/BlogPost.java:32: error:  expected
  Arrays.sort(blogPosts);
             ^
./com/example/BlogPost.java:32: error:  expected
  Arrays.sort(blogPosts);
                       ^
./com/example/BlogPost.java:32: error: cannot find symbol
  Arrays.sort(blogPosts);
              ^
  symbol:   class blogPosts
  location: class BlogPost
./com/example/BlogPost.java:32: error: cannot find symbol
  Arrays.sort(blogPosts);
        ^
  symbol:   class sort
  location: class Arrays
./com/example/BlogPost.java:31: error: cannot find symbol
  BlogPost[] blogPosts = {blogPost, secondBlogPost};
                          ^
  symbol:   variable blogPost
  location: class BlogPost
./com/example/BlogPost.java:31: error: cannot find symbol
  BlogPost[] blogPosts = {blogPost, secondBlogPost};
                                    ^
  symbol:   variable secondBlogPost
  location: class BlogPost
6 errors
com/example/BlogPost.java
package com.example;

import java.util.Date;
import java.util.Arrays;

public class BlogPost implements Comparable{
  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;
  } 
 @Override
  public int compareTo (Object obj) {
    BlogPost other = (BlogPost) obj;
     int compareCreationDate = mCreationDate.compareTo(other.mCreationDate);
    if (equals(other)) {
    return 0;
    } else {
      return mCreationDate.compareTo(other.mCreationDate);
    }
  }

  BlogPost[] blogPosts = {blogPost, secondBlogPost};
  Arrays.sort(blogPosts);

  public String[] getWords() {
    return mBody.split("\\s+");
  }

  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;
  }
}

3 Answers

Julian Garcia
Julian Garcia
18,380 Points

Hi,

you just need to include the comparison of dates inside if statement:

  @Override
  public int compareTo(Object obj) {
    BlogPost blogpost =(BlogPost) obj;
    if(equals(blogpost)) {
     return 0;
    }      
    int res = mCreationDate.compareTo(blogpost.mCreationDate);
    if(res==0){
      return mBody.compareTo(blogpost.mBody);
    }
      return res;
  }
}

Hope this help.

I tried this code but still got an error message 'Expected -1 but received 1, when comparing Sun Jul 20 20:18:00 UTC 1969 to Mon Mar 09 16:00:00 UTC 2015'

ok that worked thanks, can you explain what return res is doing?

Patrick VanVorce
Patrick VanVorce
1,952 Points

Melissa,

It is returning the result from the compareTo of the Creation Dates.

Julian Garcia
Julian Garcia
18,380 Points

The logic will be something like: 1.- Compare if the current object is equal to blogpost. If they are equal each other then return 0.

if(equals(blogpost)) {
     return 0;
    }      

2.- if they are not the same, compare creation date, mCreationDate, of both.

    int res = mCreationDate.compareTo(blogpost.mCreationDate);

3.- if both creation dates are equal then test the equality of the body

if(res==0){
      return mBody.compareTo(blogpost.mBody);
    }

if none of the above passed then return the first comparison that failed, in this case the result in res:

return res;
Patrick VanVorce
Patrick VanVorce
1,952 Points

Hey Melissa,

Make sure at the end of the method compareTo, return res or whatever variable name you used. If you have it say return 1 at the end of the method, you will continue to see that message saying "Expected -1 but received 1, ... "

this is driving me insane!!!!!!!! my code is the same at this but yet im gettin g20 errors this was not very well explained in the tutorials at all. They expect you to know, if I knew i wouldn't be watching these tutorials.