Upgrade Comparable to Use Generics

Question

Hi. I've tried this one but I'm stuck. Thanks in advance for any help. :-)

com/example/BlogPost.java

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

Answer 1 · 2015-07-24T22:06:39Z

July 24, 2015 10:06pm

Your code must compare the this instance and the instance received in compareTo method. You don't have to cast obj to BlogPost because it is already a BlogPost. The code may look like this:

public int compareTo(BlogPost obj) {
    if (this.equals(obj)) {
      return 0;
    }
    return this.mCreationDate.compareTo(obj.mCreationDate);
  }

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Sean Flanagan

Sean Flanagan

Upgrade Comparable to Use Generics

1 Answer

Enrique Munguía

Enrique Munguía

Sean Flanagan

Sean Flanagan