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!

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

Interface challenge part 2

I forgot what it means to cast in this challenge. It asks to cast the object passed in to a com.example.BlogPost?

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 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 int compareTo(Object obj){

  return 1;

  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;

1 Answer

Hi, you cast when u want to give an object the methods/properties of another object. Object is a super class. in this example u need to cast another object, let’s call this variable β€œother” to be of type BlogPost.
the working cold is this :

  public int compareTo(Object obj) {

    BlogPost other = (BlogPost) obj;
    if(equals(other) {
      return 0;

    return 1;