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Java Java Data Structures - Retired Getting There Type Casting

Marcus Schumacher
Marcus Schumacher
16,616 Points
Posted by Marcus Schumacher
Marcus Schumacher
16,616 Points

Stuck on Java Type Casting

Here is the prompt:

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

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

christopher vaughan
christopher vaughan
1,411 Points
christopher vaughan
christopher vaughan
1,411 Points

hi marcus,

see the comments and corrected code below. 

    if(obj instanceof String) {            //if it's a string
      result = (String) obj;               //return a string
    }else if(obj instanceof BlogPost) {    //if it's a blogpost
      BlogPost b = (BlogPost) obj;        //cast it to a blogpost
      result = b.getTitle();            //return the value of getTitle(which will be a string)
    }