Now that we know about Generics, let's upgrade our Comparable interface defined on the BlogPost class to use it. Rememb

To specify type with generics, you use angle brackets:

Comparable<BlogPost>

Specifying BlogPost for Comparable will let you update the parameter for the compareTo method as well as get rid of the down cast as it will now be expecting a type of BlogPost.

public int compareTo(BlogPost other) {

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

}

Spoiler Alert!

package com.example;

import java.io.Serializable;
import java.util.Date;

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("[^\\w']+");
  }

  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;
  }
}

You need to make changes in two locations -- be sure to pay attention to camel case.

public class BlogPost implements Comparable<BlogPost>, Serializable {

@Override public int compareTo(BlogPost other) { BlogPost other = (BlogPost) obj; if (equals(other)) { return 0;

Comparable<BlogPost>

@Override public int compareTo(BlogPost other) { if (equals(other)) {

Can someone explain this better? Like Matthew, I'm also stuck

As Dan has explained, you need to specify type with generics, using bracket angle. So the first change will be like;

public class BlogPost implements Comparable<BlogPost>, Serializable {

Now for the compareTo method, you get rid of the downcast by implementing a type of BlogPost

public int compareTo(BlogPost other) {

PS: This is my first Forum post, excuse me if I break some rules.

package com.example;

import java.io.Serializable; import java.util.Date;

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("[^\w']+"); }

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; } }

The first thing we need to make interface Comparable generic. To make it generic : Comparable<T> Comparable interface is implemented by class BlogPost here, so we will use Type variable(Object) BlogPost of class BlogPost. So, we will use Comparable<BlogPost> \ Here BlogPost is Object or Type variable of Class BlogPost

Then in compareTo Method:

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

we need to change Object with BlogPost and need to remove type casting:

public int compareTo(BlogPost blogPost) { BlogPost other = blogPost;

Why not public int compareTo<BlogPost other>