Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Data Structures Organizing Data Comparable

Leo Marco Corpuz
Leo Marco Corpuz
18,975 Points
Posted by Leo Marco Corpuz
Leo Marco Corpuz
18,975 Points

Sorting dates

Iā€™m not sure how to do this part of the challenge. I got lost when watching this part of the lecture.

com/example/BlogPost.java 
package com.example;

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 int compareTo(Object obj){
  BlogPost castObj=(BlogPost)obj;
  if(equals(castObj)){
  return 0;
  }

  return 1;
  }
  public BlogPost(String author, String title, String body, String category, Date creationDate) {
    mAuthor = author;
    mTitle = title;
    mBody = body;
    mCategory = category;
    mCreationDate = creationDate;
  }

  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

Tonnie Fanadez
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points
Tonnie Fanadez
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points

Part Three

Use compareTo() method to return either a negative or a positive int depending on whether the first object is less or greater than the second.

Hope this clarifies.

public int compareTo(Object other){
    BlogPost post =(BlogPost)other;

    if(equals(other)){
    return 0;
    }
  return mCreationDate.compareTo(post.getCreationDate());
  }

See you around.

Tonnie Fanadez
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points
Tonnie Fanadez
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points

Hi Leo Marco Corpuz

Part 1 is the easiest part; you just use keywords implements Comparable to make class BlogPost implement Comparable Interface.

public class BlogPost implements Comparable {}

You then generate the compareTo() method with an int as the return type.

public int compareTo(Object other){ return 1; }

Tonnie Fanadez
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points
Tonnie Fanadez
.a{fill-rule:evenodd;}techdegree seal-36
Tonnie Fanadez
UX Design Techdegree Graduate 22,796 Points

Part Two

We down cast the Object other to a BlogPost and then check if the current (this) BlogPost object is equal to the other BlogPost Object. If the BlogPost Objects are equal we return 0 - zero.

  public int compareTo(Object other){
    BlogPost post =(BlogPost)other;

    if(equals(other)){ 
     //you could also write the above line as --->>> if(this.equals(other)){}
    return 0;
    }
  return 1;
  }