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Java Java Data Structures - Retired Getting There Type Casting

Omar Amin
PLUS
Omar Amin
Courses Plus Student 1,194 Points

Don't understand what is asked

Hi guys, I am doing the second task in the "Type Casting" exercise in the Java Data Structures course and I can't really understand what is being asked. This is the question:

"Now make sure that if a com.example.BlogPost is passed in for obj that you then cast it to a BlogPost. Return the results of the getTitle method on the newly type-casted BlogPost instance.

I've included BlogPost.java for your reference only." Isn't com.example.BlogPost the way to address the class when importing? If so then how it can be passed as a parameter for a method? It's confusing a little bit.

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 String) {
     result = (String) obj;

     } 
       return result;

  }
}

1 Answer

Joshua O'Brian
Joshua O'Brian
20,747 Points

You need to see if the object is an instance of BlogPost then you need to cast it to a BlogPost and then get the Title. This way it is returning the proper String

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