Protected Access Modifier — Cross-Package Rules | Oracle Certified Professional Java SE 17 Explained
This 1Z0-829 practice question tests your understanding of utilizing java object-oriented approach. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
// File: com/example/animals/Dog.java
package com.example.animals;
public class Dog extends Animal {
public void bark() {
System.out.println("Woof");
}
}
// File: com/example/animals/Animal.java
package com.example.animals;
public class Animal {
protected void makeSound() {
System.out.println("Some sound");
}
}
// File: com/example/test/Main.java
package com.example.test;
import com.example.animals.Dog;
public class Main {
public static void main(String[] args) {
Dog dog = new Dog();
dog.makeSound(); // Line 8
}
}
Refer to the exhibit. What is the result of compiling and running the Main class?
Exhibit
// File: com/example/animals/Dog.java
package com.example.animals;
public class Dog extends Animal {
public void bark() {
System.out.println("Woof");
}
}
// File: com/example/animals/Animal.java
package com.example.animals;
public class Animal {
protected void makeSound() {
System.out.println("Some sound");
}
}
// File: com/example/test/Main.java
package com.example.test;
import com.example.animals.Dog;
public class Main {
public static void main(String[] args) {
Dog dog = new Dog();
dog.makeSound(); // Line 8
}
}
A
Runtime exception because makeSound() is not accessible.
Why wrong: The error is at compile time, not runtime.
B
Compilation error because Dog does not override makeSound().
Why wrong: Dog inherits makeSound() but does not need to override it.
C
Compilation error at line 8 because makeSound() has protected access.
The protected method makeSound() is not accessible from a different package unless through inheritance. Main is not a subclass of Animal.
D
Prints "Some sound".
Why wrong: Access is denied because Main is in a different package and not a subclass.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Compilation error at line 8 because makeSound() has protected access.
Option C is correct because the `makeSound()` method in the `Animal` class has `protected` access, and the `Dog` class is in a different package. In Java, a `protected` member is accessible only within the same package or through inheritance in a subclass, but only if the access is via a reference of the subclass type. In the `Main` class, the reference is of type `Animal` (line 8), not `Dog`, so the compiler cannot access the `protected` method from a different package, resulting in a compilation error.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Runtime exception because makeSound() is not accessible.
Why it's wrong here
The error is at compile time, not runtime.
✗
Compilation error because Dog does not override makeSound().
Why it's wrong here
Dog inherits makeSound() but does not need to override it.
✓
Compilation error at line 8 because makeSound() has protected access.
Why this is correct
The protected method makeSound() is not accessible from a different package unless through inheritance. Main is not a subclass of Animal.
Related concept
Read the scenario before looking for a memorised answer.
✗
Prints "Some sound".
Why it's wrong here
Access is denied because Main is in a different package and not a subclass.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Oracle often tests the subtle rule that `protected` access from a different package requires the reference type to be the subclass itself, not the superclass, leading candidates to mistakenly think inheritance alone is sufficient.
Detailed technical explanation
How to think about this question
The Java Language Specification (JLS §6.6.2) states that a `protected` member of a class in another package is accessible only within subclasses, and only when the access is through a reference of the subclass type (or a subclass thereof). This rule prevents accessing a `protected` member via a superclass reference from a different package, ensuring encapsulation. In real-world scenarios, this often arises in framework design where base classes expose `protected` hooks for subclasses, but external code must use the subclass type to invoke them.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-829 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Utilizing Java Object-Oriented Approach — This question tests Utilizing Java Object-Oriented Approach — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Compilation error at line 8 because makeSound() has protected access. — Option C is correct because the `makeSound()` method in the `Animal` class has `protected` access, and the `Dog` class is in a different package. In Java, a `protected` member is accessible only within the same package or through inheritance in a subclass, but only if the access is via a reference of the subclass type. In the `Main` class, the reference is of type `Animal` (line 8), not `Dog`, so the compiler cannot access the `protected` method from a different package, resulting in a compilation error.
What should I do if I get this 1Z0-829 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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