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 - Retired Getting There Type Casting

Heather Gray
Heather Gray
6,225 Points
Posted by Heather Gray
Heather Gray
6,225 Points

Cast as blogpost?

No idea why this isn't working for task 2. Tried multiple strange things. I think this should work, but it's obviously wrong.

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

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

Hi Heather, There are a some syntax and structural issues with the code.

  • The if blocks need to be wrapped in curly braces{}
  • The getTitleFromObject method returns a String. In the second if, can't return type BlogPost as String. Need to recast obj to BlogPost first, then call the getTitle() method and return the String result

I've left the last statement for you to complete.

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) {
    if (obj instanceof String) {  // <-- missing curly braces around 'if' block
      return (String) obj;
    }
    if (obj instanceof BlogPost) {  // <-- missing curly braces around 'if' block
      // cast obj to BlogPost object
      BlogPost post = (BlogPost) obj;
      // return post getTitle() results
      return // Can you figure out what goes here?
    }
    String result = "";
    return result;
  }
}

Post back if still stuck. Good Luck!

Heather Gray
Heather Gray
6,225 Points
Heather Gray
Heather Gray
6,225 Points

I did it! Thanks for your help.