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Java Java Data Structures Getting There Type Casting

Posted by Mat T'Qartit
Mat T'Qartit
29,277 Points

BlogPost casting throws an error: Oops! It looks like Task1 is no longer passing..?

I don't see what I'm missing here.. I think that bp.getTitle() might have nothing but at least I was expecting an error message which would be helpful...?

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;

public class TypeCastChecker {
  /***************
  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;

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

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

The error message is actually correct, your code is fine as far as task 2 is concerned, but your code is no longer passing the first task. Which was to check if the Object passed in was a String and cast it as such if that was the case.

Currently your code only checks if obj is a BlogPost, if you also add a check that tests if it's a String like this:

import com.example.BlogPost;

public class TypeCastChecker {
  /***************
  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;

  public static String getTitleFromObject(Object obj) {
    // Fix this result variable to be the correct string.
    String result = "";

    if(obj instanceof String) { // Check if obj is String
      result = (String)obj; // Cast it as such if that is the case
    }


    if(obj instanceof BlogPost) {
      BlogPost bp = (BlogPost)obj;
      result = bp.getTitle();
    }
    return result;
  }
}

Then your code will pass.

Mat T'Qartit
Mat T'Qartit
29,277 Points

oh yeah.. makes sense now... Thanks!