Oracle Certified Professional Java Se 11 Developer · Free Practice Question Hard
Question 74
Question ID: UKOCP42179
Given code of LogHelper.java file:
- package com.udayankhattry.ocp;
- abstract class Helper {
- int num = 100;
- String operation = null;
- protected abstract void help();
- void log() {
- System.out.println("Helper-log");
- }
- }
- public class LogHelper extends Helper {
- private int num = 200;
- protected String operation = "LOGGING";
- void help() {
- System.out.println("LogHelper-help");
- }
- void log() {
- System.out.println("LogHelper-log");
- }
- public static void main(String [] args) {
- new LogHelper().help();
- }
- }
Which of the following changes, done independently, allows the code to compile and on execution prints LogHelper-help?
Select 3 options.
- A Remove the private modifier from the num variable of LogHelper class
- B Remove the protected modifier from the operation variable of LogHelper class
- C Remove the protected modifier from the help() method of Helper class
- D Add the protected modifier to the log() method of Helper class
- E Add the protected modifier to the help() method of LogHelper class
- F Add the public modifier to the help() method of LogHelper class
-
G
Add the public modifier to the log() method of LogHelper class
-
H
Add the protected modifier to the log() method of LogHelper class
Reveal correct answers
Correct answers: C, E, F
Explanation
UKOCP42179:
Let us first find out the issue:
As instance variables are hidden by subclasses and not overridden, hence overriding rules are not for the instance variables. There are no issues with variables 'num' and 'operation'.
log() method is declared with default modifier in both the classes, hence no issue with log() method as well.
abstract method help() is declared with protected modifier in Helper class and in LogHelper class, it is overridden with default modifier and this causes compilation error. So below solutions to resolved this issue:
1. Remove the protected modifier from the help() method of Helper class: Both the overridden and overriding methods will have same default modifier, which is allowed
OR
2. Add the protected modifier to the help() method of LogHelper class: Both the overridden and overriding methods will have same protected modifier, which is allowed
OR
3. Add the public modifier to the help() method of LogHelper class: Overridden method will have protected modifier and overriding method will have public modifier, which is allowed
Discussion
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