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Start your free trialBjorn Van de Weyngaert
1,297 PointsBlogPost typecasting
I'm stuck at the 2nd challenge of the last exercise on "Getting There" of the Java Data Structures course.
I keep getting the wrong result. Any suggestions?
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;
}
}
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) {
boolean objIsString = obj instanceof String;
boolean objIsBlogPost = obj instanceof BlogPost;
String result = "";
if (objIsString == true) {
result = (String)obj;
}
if (objIsBlogPost == true) {
result = ((BlogPost)obj).toString();
}
return result;
}
}
1 Answer
andren
28,558 PointsYour code is practically correct. The only issue is that the instructions specified that when a BlogPost object is passed in it wants the title of the BlogPost to be returned, not the toString
version of the BlogPost
.
You can get the title of the BlogPost
by calling its getTitle
method, like this:
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) {
boolean objIsString = obj instanceof String;
boolean objIsBlogPost = obj instanceof BlogPost;
String result = "";
if (objIsString) {
result = (String)obj;
}
if (objIsBlogPost) {
result = ((BlogPost)obj).getTitle(); // toString replaced with getTitle
}
return result;
}
}
You might also notice that I removed the == true
part of your conditions due to them being unnecessary. The result of the instanceof
keyword is by itself a boolean so you don't have to compare it to anything to make the if
statements work.