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Java Java Data Structures Getting There Type Casting

Posted by remi poolen
remi poolen
6,697 Points

can someone explain the 2/2 assignment?

how do i return the BlogPost object as result whilst result is defined as a String?

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

  }
}

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

You are't supposed to return the BlogPost object itself. The challenge instruction states:

Return the results of the getTitle method on the newly type-casted BlogPost instance.

So when you receive a BlogPost object you are meant to cast it and then set result equal to the title of the blogPost.

Like this:

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

  }
}