Totally stumped on challenge task 1 of 2 for casting

Question

Hi,

I'm having lots of difficulty with this challenge. If you notice the code I added starts right after the comment about fixing this result variable. Here is my code. Thanks for the help!

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.
   public static String getTitleFromObject(Object obj) {
    // Fix this return statement to be the correct string.
    if (obj instanceof String) {
      return (String) obj;
    } else {
      return ((BlogPost) obj).getTitle(); 
    }


  }
}

Answer 1 · 2015-08-30T18:20:34Z

August 30, 2015 6:20pm

Hello Gabriel,

The issue you are having is due to the return statement being wrapped within the else clause. A method that requires a returned type must have a return statement that is not out of scope. While we can write code with multiple return statements, the challenge is asking for you to stick to a good code writing convention that calls for only using one return. Furthermore, it is teaching a better way to cast variables for their use within the method.

Here are some examples:

An altered version of your code that allows it to work:

 public static String getTitleFromObject(Object obj) {
    // Fix this return statement to be the correct string.
    if (obj instanceof String) {
      return (String) obj;
    } else if (obj instanceof BlogPost) {
      return ((BlogPost) obj).getTitle(); 
    }
      return "";  // notice that we have to provide the ability to get to this line and return outside of the if/else block
  }

However, the challenge provided the String result for the purpose of teaching a better code writing convention. Here is an example:

 public static String getTitleFromObject(Object obj) {
    // We provide a default String to return if we do not get one of the desired objects
    String result = "";
    if (obj instanceof String) {
     // If obj is an instance of String, we cast it to a String and assign it to result
       result = (String)obj;
    } else if (obj instanceof BlogPost) {
     // If obj is an instance of a BlogPost, we cast it to a BlogPost and assign it to post
      BlogPost post = (BlogPost)obj;
     // Now that we have a BlogPost named post. We can call its method to get the title
     // and assign it to result 
      result = post.getTitle();
    }
    // We only have one return statement. This allows our code to be much clearer.
    return result;
  }

Please let me know if this helps.

Regards,

Chris

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Gabriel E

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Totally stumped on challenge task 1 of 2 for casting

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