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Java Java Data Structures - Retired Organizing Data Comparable

Solomon Asiedu-Ofei Jnr
Solomon Asiedu-Ofei Jnr
1,015 Points

Error on

I keep getting this error

./com/example/BlogPost.java:20: error: method does not override or implement a method from a supertype @Override ^

What super type are they referring to?

com/example/BlogPost.java
package com.example;

import java.util.Date;

public class BlogPost {
  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;
  }

@Override
  public int compareTo(Object obj) { 
  BlogPost post = (BlogPost) obj;
    if(equals(post)) {
  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;
  }
}

3 Answers

Chase Carnaroli
Chase Carnaroli
5,139 Points

Actually try this. I think @Trent had the right idea with implementing comparable, but it wasn't equals(post) that is the issue, comparable just wasn't implemented correctly.

Try this:

public class BlogPost implements Comparable {
    // Other code
    . . .

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

your class does not extend or implement anything, so it can not override anything. You need to implement Comparable.

public class BlogPost implements Comparable { // random code in here }

Solomon Asiedu-Ofei Jnr
Solomon Asiedu-Ofei Jnr
1,015 Points

hey Trent I did this but its not working.

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

I think you are probably getting the error in your if statement instead of if(equals(post)) do if (obj.equals(post))

Chase Carnaroli
Chase Carnaroli
5,139 Points

I don't think you need @Override at all in your code.... Try deleting that and see if it works.

Edit: I added what I think the code should look like in order to compile

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

I think it was because he did equals(post) instead of obj.equals(post)

Chase Carnaroli
Chase Carnaroli
5,139 Points

No, equals(post) should be fine.
He doesn't actually need to put an object before that method because it is inside of a class.
Since it is inside of a class, writing equals(post) is the same as writing this.equals(post) both of which are valid code.

Chase Carnaroli
Chase Carnaroli
5,139 Points

Actually obj.equals(post) would not work at all.
obj and post are the same thing. The only difference is that post is cast as a BlogPost