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Anish Palan
3,157 PointsCannot find symbol error while calling getTitle method
I am using this code:
if (obj instanceof BlogPost) { result=obj.getTitle(); } return result. But it shows a cannot find symbol error for getTitle method
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) {
// Fix this result variable to be the correct string.
String result = "";
if (obj instanceof com.example.BlogPost)
{
result=obj.getTitle();}
return result;
}
}
2 Answers
Grigorij Schleifer
10,365 PointsHi Anish,
I commented the code a little bit:
public static String getTitleFromObject(Object obj) {
// the method accepts an object as the argument
// we know the type of the object (BlogPost or String ....)
// but the compiler has no clue at all
String result = "";
if (obj instanceof BlogPost) {
// no need for dot notation just space and instancef (all downcased)
BlogPost bp = (BlogPost) obj;
// so if argument is a BlogPost
// cast it to BlogPost
result += bp.getTitle();
// get the Title using the getTitle method
}
if (obj instanceof String) {
// if obj is a String
// cast it to String
result += (String) obj;
}
return result;
// return the result
}
Makes sense?
Grigorij
Kourosh Raeen
23,733 PointsBased on the instructions, you need to see if the object is of type String. If it is then cast it to String and then return it:
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 = "";
if (obj instanceof String) {
result = (String) obj ;
}
return result;
}
}
Anish Palan
3,157 PointsYes,but in the second part of exercise it asks to check if object passed is of type BlogPost. If yes, cast it and run the getTitle method.
Kourosh Raeen
23,733 PointsFor the second part, cast it to BlogPost before calling getTittle():
public static String getTitleFromObject(Object obj) {
// Fix this result variable to be the correct string.
String result = "";
if (obj instanceof String) {
result = (String) obj ;
}
if (obj instanceof BlogPost) {
result = ((BlogPost) obj).getTitle() ;
}
return result;
}