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Java Java Data Structures Getting There Type Casting

Omar Amin
PLUS
Omar Amin
Courses Plus Student 1,194 Points
Posted by Omar Amin
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
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;
  }
}