A question about equals

Question

Hi in this if I make a equals(other)

But I don't understad what the equals compare 'other' to?

Usually I see 'example.equals(hamster)' I googles it but all example shows the same as mine... How does this works?

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 BlogPost(String author, String title, String body, String category, Date creationDate) {
    mAuthor = author;
    mTitle = title;
    mBody = body;
    mCategory = category;
    mCreationDate = creationDate;
  }
  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 · 2018-03-23T14:51:43Z

March 23, 2018 2:51pm

Hi Timmie,

The compareTo method is comparing the instance of BlogPost that compareTo is being called on, to the argument passed in.

So, to use compareTo, you need to create an instance of BlogPost first. It is that instance which is compared to the obj.

You can make this clearer by using the this keyword to indicate you are using the instance of the class:

  public int compareTo(Object obj){
    if(this.equals((BlogPost) obj)){
      return 0;
    }
    return 1;
  }

Make sense?

Steve.

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Timmie Nilsson

Timmie Nilsson

A question about equals

1 Answer

Steve Hunter

Steve Hunter

Timmie Nilsson

Timmie Nilsson