please help me to solve this challenge

Question

// i am not able to understand the challenge

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 = "";
    return result;
  }
}

Answer 1 · 2015-10-26T15:51:56Z

October 26, 2015 3:51pm

Hi Neelesh,

The first question is: The method getTitleFromObject will be called and passed a String and/or a com.example.BlogPost. For this first task, return the object obj type casted as a String if it is in fact a String.

There are two hints that you can see in the code. Start by setting the first one to true and clicking Check Work. You'll get a hint that says: HINT 1: You can check the type of an object using the instanceof keyword. What if you tried if (obj instanceof String) {...?

OK - set the true marker back to false. SO, if the obj is a String return it as a String - else ... well, we'll worry about that in a minute! The first part clearly needs an if test. We're testing if obj is a String:

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

That code does what the question asks - using the HINT as guidance - if the obj is a String return it cast as a String. Make sense?

Right, now change the other false to true nd see what the question and hint are:

Q: 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.

HINT: (I can't get that to work ... sorry!

So the question wants to act on a BlogPost - that means we're in the else part of the if statement as there are only two possibilities of the type of obj, String or BlogPost. So, we want to cast obj to a BlogPost then call the getTitle() method on it. OK? here's the cast:

(BlogPost) obj

So that is a BlogPost. We want to call a method on it:

((BlogPost) obj).getTitle();

That's what needs returning out of the else clause.

The completed code, for the whole if statement, looks like:

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

Delete the last two lines regarding results and make sure both your hints are set to false.

That should see you through it! A tough challenge.

I hope that made sense.

Steve.

Welcome to the Treehouse Community

Looking to learn something new?

Neelesh Tewani

Neelesh Tewani

please help me to solve this challenge

1 Answer

Steve Hunter

Steve Hunter

Gonzalo Torres del Fierro

Gonzalo Torres del Fierro

Steve Hunter

Steve Hunter