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Java Java Data Structures Getting There Type Casting

Are we returning a Boolean and is their some type of data coming into the method?

Title pretty much says it all

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 boolean getTitleFromObject() {

    if(

  }

    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 return statement to be the correct string.
    return "";
  }
}

1 Answer

Rob Bridges
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Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points

Hey there Forrest,

One thing I am seeing is that you are trying to create the getTitleFromObject from the BlogPost.java, go ahead and delete the method that you crated. in there.

In the TypeCastChecker.java we have the skeleton code for it.

public static String getTitleFromObject(Object obj) {

    return "";
  }

So first things first, our directions want us to check if the object is an instance of a String and return it as a String if it is. We can do this by the first if statement of

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

Secondly it's wanting us to check to see if the object is an instance of a BlogPost, we just modify our code above and check, but we run into troubles, because it's not sure we're calling getTitle() on a BlogPost object, this is easily remedied by type casting the variable like in the second if statement.

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

After that, your code should look similar to

public static String getTitleFromObject(Object obj) {
    if (obj instanceof String) {
      return (String) obj;
    }
    else if (obj instanceof BlogPost) {
      BlogPost myBlogPost = (BlogPost) obj;
      return myBlogPost.getTitle();
    }
    return "";
  }
}

Which works great for this challenge, let me know if there's any trouble with this answer and I'll try to improve it.