Logical error

Question

I am getting error that " Everything is correct but the 1 st task wont pass". I added return result; inside the if statement because i was not able to ask for help with the above error(some sort of bug ).

Can anyone tell me what logical mistake im doing?. Thanks in advance!

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 BlogPost) {
     BlogPost another = (BlogPost) obj; 
     result= (String) obj;
     return another.getTitle();
      return result;
    }
     return result;

  }
}

Answer 1 · 2016-04-24T08:56:41Z

April 24, 2016 8:56am

I think that is better placed inside a single if/else statement. The question states that the method can only be passed a BlogPost or a String, so a failed test for one can safely assume the other. Have a look at my post here that makes that assumption too. (So I'm agreeing with myself!!).

So, we can do this in a few lines of code - this is the same as above, just a bit neater:

    if(obj instanceof String){
      return (String) obj;
    } else {
      return ((BlogPost) obj).getTitle();
    }

Steve.

Answer 2 · 2016-04-23T15:42:47Z

April 23, 2016 3:42pm

Hi Ronit,

Let's start with the string part; you want to use instanceof inside the if statement to check that obj is a String. If it is, cast it then return it:

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

A similar process can be done with the BlogPost task. I did this as a separate if statement - I don't see that they need to be joined but, assuming mutual exclusivity (i.e. obj can only be a String or a BlogPost), you can use the else clause of the above if statement. I opted for the safer method and tested for BlogPost separately. I did the same as with the String - use instanceof to test if obj is a BlogPost, if it is, follow the instructions; 1. cast to BlogPost, 2. return the result of calling the getTitle() method on it. In one line, that look like:

    if(obj instanceof BlogPost){
      return ((BlogPost) obj).getTitle();
    }

I hope that helps.

Steve.

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Ronit Mankad

Ronit Mankad

Logical error

2 Answers

Steve Hunter

Steve Hunter

Steve Hunter

Steve Hunter

Ronit Mankad

Ronit Mankad