Hi, I have Casted the given object to blogpost type object and checked for equality and return 1.

Question

Hi, please help i have casted the given object to BlogPost object and checked for equality and return the value of 1.please check my code and provide the solution for this.

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 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;
  }

  @Override
  public int compareTo(Object obj){
    BlogPost ob = (BlogPost) obj;
    if(obj==ob){
     return 0; 
    }
   return 1; 
  }

}

Answer 1 · 2018-01-27T12:08:43Z

January 27, 2018 12:08pm

You are comparing obj which is the passed in object to ob which is the passed in object cast as a BlogPost. In other words you are comparing the passed in object against itself. Casting an object does not change its contents, only how Java treats it. Also you should ideally use the equals method to compare objects, rather than using ==.

The two objects you are meant to compare is the object that the compareTo method belongs to and the passed in object. To reference the object that the method belongs to you can use the this keyword. Like this:

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

However using the this keyword is technically optional since Java is smart enough to figure out that you are calling a method found within the same object even if you omit it. Like this:

@Override
public int compareTo(Object obj){
  BlogPost ob = (BlogPost) obj;
  if(equals(ob)){
    return 0; 
  }
  return 1; 
}

Omitting this is pretty common but you can use it if you feel it makes the code easier to read, either of those two examples posted above will let you pass the second task.

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Udayakumar T

Udayakumar T

Hi, I have Casted the given object to blogpost type object and checked for equality and return 1.

1 Answer

andren

andren