Totally lost on Java problem

Question

Prompt:

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.

I not only don't know what to code here, I have no idea what is going on at all. Care to provide a little explanation for a newb? Thanks! :D

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 · 2016-10-02T04:41:58Z

October 2, 2016 4:41am

For the method getTitleFromObject(Object obj) obj is passed. Notice the type of the parameter , it is Object. In java every thing inherits from Object. So you can pass any object to the method getTitleFromObject(Object obj).

In this case , the object that can be passed is either String or BlogPost. To check what kind of object is it one can use the instanceof operator.

If the object passed is a String , downcast from Object to String using this notation (String)obj

public static String getTitleFromObject(Object obj) {
    // Fix this result variable to be the correct string.
    String result = null;
    if(obj instanceof  String) {
    result = (String) obj;
    }
    return result;
  }

Refer [http://stackoverflow.com/questions/380813/downcasting-in-java] for more info regarding the casting.

Answer 2 · 2016-10-02T14:59:52Z

October 2, 2016 2:59pm

Thanks! That helped :)

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Marcus Schumacher

Marcus Schumacher

Totally lost on Java problem

2 Answers

Teja Tummalapalli

Teja Tummalapalli

Marcus Schumacher

Marcus Schumacher