Can someone tell me what is the other here? I cannot get this to work

Question

Can some tell me what is this other object? Are we creating a new blogpost object called other?

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

Answer 1 · 2015-05-18T17:05:06Z

May 18, 2015 5:05pm

The idea here is that you get an object as a parameter and you cast into a BlogPost object. Now you have 2 BlogPost objects; the current one (this) and the one you got from the parameter. Since you now have 2 objects you can compare them and return accordingly.

So you'd want to the casting before and outside the if clause because it's essential that you have 2 objects of similar type in order to compare them to one another.

Another error here is that you are trying to cast an Object-type object into a BlogPost object, but you store the result back into an Object-type variable. So in essence you haven't done anything here. What you need to do is store the result into a BlogPost variable (since that's what you are trying to cast it into).

Finally, what you want to do is compare the current objects (this) mCreationDate attribute with the parameterized objects' mCreationDate attribute.

Here is what I tried:

public int compareTo(Object obj) {
  BlogPost otherObj = (BlogPost) obj;  //typecast the parameter into a BlogPost object
  if (this.equals(otherObj)){
    return 0;
  }
  return mCreationDate.compareTo(otherObj.getCreationDate());  //compare this.mCreationDate with the parameterized objects' mCreationDate value
}

Hope this helps! :)

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Ieva Salte

Ieva Salte

Can someone tell me what is the other here? I cannot get this to work

1 Answer

Christian Andersson

Christian Andersson