- A
A sealed class restricts which other classes or interfaces may extend or implement it.
Sealed classes explicitly define permitted subclasses.
- B
A sealed interface cannot use the permits clause.
Why wrong: Sealed interfaces can use permits.
- C
A subclass of a sealed class must be declared as final, sealed, or non-sealed.
That is true, but option C is actually correct? Wait, I need to re-check. In Java 17, direct subclasses of a sealed class must be final, sealed, or non-sealed. So C is actually true. But the question is 'Which TWO', so I need to adjust. Let me correct: Actually, C is true. So the correct pair would be A and C. But I already set A and D. I need to fix. Let me recompute: The correct statements are A and C. D is false because the permits clause is optional if the subclasses are in the same file. So correct: A and C. I'll update the options accordingly.
- D
The permits clause must list all direct subclasses of a sealed class.
Why wrong: If the subclasses are in the same source file, the permits clause can be omitted.
- E
A sealed class must be declared as abstract.
Why wrong: Sealed classes can be concrete or abstract.
1Z0-829 Utilizing Java Object-Oriented Approach Practice Question
This 1Z0-829 practice question tests your understanding of utilizing java object-oriented approach. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO statements are true about the sealed class feature in Java 17?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A sealed class restricts which other classes or interfaces may extend or implement it.
Option A is correct because the primary purpose of the sealed class feature is to explicitly control which other classes or interfaces are permitted to extend or implement it. This is achieved by using the `permits` clause to list the allowed subclasses, thereby restricting the inheritance hierarchy.
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.
- ✓
A sealed class restricts which other classes or interfaces may extend or implement it.
Why this is correct
Sealed classes explicitly define permitted subclasses.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A sealed interface cannot use the permits clause.
Why it's wrong here
Sealed interfaces can use permits.
- ✓
A subclass of a sealed class must be declared as final, sealed, or non-sealed.
Why this is correct
That is true, but option C is actually correct? Wait, I need to re-check. In Java 17, direct subclasses of a sealed class must be final, sealed, or non-sealed. So C is actually true. But the question is 'Which TWO', so I need to adjust. Let me correct: Actually, C is true. So the correct pair would be A and C. But I already set A and D. I need to fix. Let me recompute: The correct statements are A and C. D is false because the permits clause is optional if the subclasses are in the same file. So correct: A and C. I'll update the options accordingly.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The permits clause must list all direct subclasses of a sealed class.
Why it's wrong here
If the subclasses are in the same source file, the permits clause can be omitted.
- ✗
A sealed class must be declared as abstract.
Why it's wrong here
Sealed classes can be concrete or abstract.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the requirements for subclasses of a sealed class, mistakenly thinking they must be `final` only, or they overlook that a sealed class can be concrete and does not need to be abstract.
Detailed technical explanation
How to think about this question
Under the hood, the sealed class feature enforces compile-time checks that ensure no unauthorized subclass exists outside the permits list, and the compiler generates a sealed descriptor in the class file. A real-world scenario is modeling a payment method hierarchy where only specific payment types (e.g., CreditCard, PayPal) are allowed, preventing arbitrary extensions that could break business logic.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
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FAQ
Questions learners often ask
What does this 1Z0-829 question test?
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: A sealed class restricts which other classes or interfaces may extend or implement it. — Option A is correct because the primary purpose of the sealed class feature is to explicitly control which other classes or interfaces are permitted to extend or implement it. This is achieved by using the `permits` clause to list the allowed subclasses, thereby restricting the inheritance hierarchy.
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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Last reviewed: Jun 11, 2026
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