Bummer! Expected -1 but received 1, when comparing Sun Jul 20 20:18:00 UTC 1969 to Mon Mar 09 16:00:00 UTC 201

Question

Mentioned below is my piece of code which is probably gving this error. Any insights please? @Override public String toString() { return String.format ("Treet: \"%s\" by %s on %s", mTitle,mCategory, mCreationDate);

}

com/example/BlogPost.java

package com.example;
import java.util.Arrays;
import java.util.Date;

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 String toString() {
return String.format ("Treet: \"%s\" by %s on %s", mTitle,mCategory, mCreationDate);

}

  @Override
  public int compareTo(Object obj) {

 BlogPost other = (BlogPost ) obj;
    if (equals(other)){

     return 0 ; 
    }
    return 1;
  }






  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;
  }
}

Answer 1 · 2016-12-30T15:02:18Z

December 30, 2016 3:02pm

This forum post has a lively discussion talking about this answer.

https://teamtreehouse.com/community/how-do-i-do-this-15

Answer 2 · 2016-12-30T15:03:37Z

December 30, 2016 3:03pm

Well, notice that your compare function does the following: If this object equals the object you are passing to the method, then it returns 0; Otherwise, if it doesn't match, it returns 1.

The exercise asks you to write a function that orders blogposts by their creation dates. So what you want to do is compare the creation dates, and remember that usually the compareTo method returns -1, 0 or 1 to establish an order between the object and the one you are comparing to.

Also, a Date object by itself also implements the Comparable interface, meaning it also has a compareTo method, so here's a possible solution:

@Override
  public int compareTo(Object obj) {
    BlogPost other = (BlogPost) obj;

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

    return mCreationDate.compareTo(other.mCreationDate);
  }

In the code you posted, you always returned 1 if the blogposts were different, so there was no way to order the blogposts, whether you did x.compareTo(y) or y.compareTo(x), the result would always be one.

Now, with the code I posted, what will happen is that x.compareTo(y) will compare the creationDates of x and y, it will return -1 if x's creationDate is before y's creation date, it will return 0 if the blog posts are equal or if the dates are the same, and it will return 1 if x's creation date is after y's creation date.

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Sameer Rao

Sameer Rao

Bummer! Expected -1 but received 1, when comparing Sun Jul 20 20:18:00 UTC 1969 to Mon Mar 09 16:00:00 UTC 201

2 Answers

Philip Gales

Philip Gales

Mauro Teixeira

Mauro Teixeira