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Java Java Data Structures Getting There Type Casting

Wan Nor Adzahari Wan Tajuddin
Wan Nor Adzahari Wan Tajuddin
2,438 Points

Why do I have to convert obj Object to String twice?

It seems that this is the correct code to pass the 1st task of the code challenge.

I just wanted to know, why do I have to convert obj to type String twice?

I did it once in line 14 which is String result = (String) obj;

And I have to do it again in the if statement which is obj = (String) obj;

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 = (String) obj;
    if (obj instanceof String) { 
      obj = (String) obj;
    }
    return result;
  }
}

1 Answer

Roque Sosa
PLUS
Roque Sosa
Courses Plus Student 1,024 Points

Hello Wan,

Dont really rember if that is correct for that exercise. As for the question with the casting of obj, what you are doing here: '''java

String result = (String) obj; ''' Is calling the obj value casted as a String meaning that for that sentence the value stored in obj is being treated as a String type obj. You are not really changing the type of obj the cast is only valuable for that sentece.

Please let me know if this was not clear enough be happy to explain ir further.