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Java Java Data Structures - Retired Getting There Type Casting

Eric Stermer
Eric Stermer
9,499 Points
Posted by Eric Stermer
Eric Stermer
9,499 Points

No idea what to do here or where to start!

I am completely lost here. I have no idea what I am doing on this task. I am so lost here I don't even know how to ask this question. What am I being required to do?

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.
    BlogPost post = (BlogPost) obj;
    String result = "";
    return result;
  }
}

1 Answer

Grigorij Schleifer
Grigorij Schleifer
10,365 Points
Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Hi Eric,

let us look at the code:

public static String getTitleFromObject(Object obj) {
    // the parameter is an Object type, so it can be every type that is an Object
    // String or BlogPost, or something else 
    // the compiler doesnt know what kind the parameter is made of
    // just we do

    String result = " ";
    // so we create a line that allows the pedantic copiler 
    // to check whether obj is a String or BlogPost
    if (obj instanceof String) {

    return (String) obj;
      // in other words: if the parameter obj a String
      // cast obj into String and return it

    } else {
// if obj is not a String return the title from BlogPost using getTitle method
      return ((BlogPost) obj).getTitle();
    } 
  }

Does it make sense?

Grigorij

Eric Stermer
Eric Stermer
9,499 Points
Eric Stermer
Eric Stermer
9,499 Points

thanks that does make sense, thanks!

Grigorij Schleifer
Grigorij Schleifer
10,365 Points
Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Hey Eric,

no Problem. See you in the Forum :)