Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Data Structures Getting There Type Casting

Damjan Vlaic
Damjan Vlaic
19,244 Points
Posted by Damjan Vlaic
Damjan Vlaic
19,244 Points

---JAVA---

someone pls help, i can't figure out what to do at this one

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. 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 = "";
    return result;
  }
}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi there,

You need to take this question literally. return the object obj cast as a String if it is a String.

Start with if it is a String - use if and instanceof to test this:

if(obj instanceof String){
  // do something
}

Inside, we want to do the cast and return it. Now, you can either set the provided variable result to the cast obj and return that after the if, or you can just return it directly. I prefer the latter but I'll give you both:

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

// or 

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

In the next task, remember the start of the requirements defined here. There are only two types that the variable obj can hold. It is either a String or a BlogPost. Don't cater for anything else.

Good luck!

Steve.

Damjan Vlaic
Damjan Vlaic
19,244 Points
Damjan Vlaic
Damjan Vlaic
19,244 Points

it worked out perfectly tnx for helping steve :)