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Java Java Data Structures - Retired Getting There Type Casting

Enyang Mercy
PLUS
Enyang Mercy
Courses Plus Student 2,339 Points

type casting Bummer! I expected the String value I passed in to be returned and it wasn't. Received ''

i cant identify the problem here

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;
    }
  public static String getTitleFromObject(Object obj) {
    String result = "";
    if (obj instanceof String) {
      result = (String) obj;
    }
    return result;
  }
}
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 = "";
    return result;
  }
}

I'm not sure what your question is exactly, the only thing I see here that explicitly has String parameter is the constructor for BlogPost.

1 Answer

Kristi Marks
Kristi Marks
1,807 Points

What you're supposed to be learning in this exercise is how to refer to a generic Object in more specific terms(downcasting). So take a look at the getTitleFromObject method. You can see it accepts a parameter of type Object, right?

Well Object is super generic. It could be a BlogPost, or a List of BlogPosts, or a PezDispenser. But getTitleFromObject wants a String back that reprensents a BlogPost Title. Hmm, so we need a way to refer to obj as a BlogPost so we can be sure it has Title property we can return as the result....

Basically, take the contents of your method in BlogPost, copy them, then paste them over the one in TypeCastChecker.

Sorry didn't see that before.