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Java Java Data Structures - Retired Getting There Type Casting

Courtney Knight
Courtney Knight
807 Points

GETTITLE METHOD. WHERE DID I GO WRONG?

I have tried to solve this chalenge for 2 days. I either get compiler errors or It says I have not solved it. Can anyone tell me where I am going wrong?

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;
    }

    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;
    }
}
TypeCastChecker.java
import com.example.BlogPost;
import java.util.Date;

public class TypeCastChecker {
   public static int compareDate;
   private static Date mCreationDate;
  /***************
  I have provided 2 hints for this challenge.
  Change `false` to `true` in one line below, then click the "Check work" button to see the hint.
  NOTE: You must set all the hints to false to complete the exercise.
  ****************/
  public static boolean HINT_1_ENABLED = false;
  public static boolean HINT_2_ENABLED = false;

 // String title = (String) obj;


  public static String getTitleFromObject(Object obj) {


      String title = "bad type";
      if(obj instanceof BlogPost) {
          BlogPost post = (BlogPost) obj;
         title = post.getTitle();

          }
      if(obj instanceof String) {
          title = (String) obj;

          }

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

  }
}

I am not familiar with this challenge so my answer may not be what you are looking for, but I do see a problem in your code! In your compareTo method, when comparing mCreationDate, you specify a private field of another object as a parameter. Specifically "other.mCreationDate". Instead, you would need to use the getter method, so your code would look like:

int compareDate = mCreationDate.compareTo(getCreationDate());

2 Answers

Michael Hess
Michael Hess
24,512 Points

Hi Courtney,

It looks like you're really close! The obj will be either a String or a BlogPost. The first case, of String, is taken care of by the if statement -- we also need to code for the second cases where obj is a BlogPost -- so we need to add an else-if statement.

Please see the following solution:

public static String getTitleFromObject(Object obj) {
    // Fix this result variable to be the correct string.
    String result = "";
    if(obj instanceof String) {
      result = (String) obj;
    } else if (obj instanceof BlogPost) {
      BlogPost temp = (BlogPost) obj;
      result = temp.getTitle();
    }
    return result;
  }

If you would like me to explain anything any further I will be happy to do so!

Craig Dennis
STAFF
Craig Dennis
Treehouse Teacher

Did you get it Courtney? Your code looks good. What error are you getting?