- A
An interface can be instantiated directly
Why wrong: Interfaces are abstract types and cannot be instantiated.
- B
An interface can extend multiple interfaces
Interfaces support multiple inheritance of type.
- C
An interface can contain static methods
Static methods are allowed in interfaces since Java 8.
- D
An interface can contain default methods
Default methods provide a default implementation in interfaces.
- E
An interface can have private fields
Why wrong: Interface fields are implicitly public static final; private fields are not supported.
Question 207 of 509
1Z0-811 Object-Oriented Programming Practice Question
This 1Z0-811 practice question tests your understanding of object-oriented programming. 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.
Which THREE statements are true about interfaces in Java? (Choose three.)
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
✓
An interface can extend multiple interfaces
Options B, C, and D are true about interfaces in Java. An interface can extend multiple interfaces using the extends keyword. Since Java 8, interfaces can contain static methods (with body) and default methods. Option A is false because interfaces cannot be instantiated directly; they must be implemented by a class. Option E is false because interface fields are implicitly public static final; private fields are not permitted in interfaces (private methods are allowed since Java 9, but not fields).
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
An interface can be instantiated directly
Why it's wrong here
Interfaces are abstract types and cannot be instantiated.
- ✓
An interface can extend multiple interfaces
Why this is correct
Interfaces support multiple inheritance of type.
Related concept
Standard ACLs match source addresses.
- ✓
An interface can contain static methods
Why this is correct
Static methods are allowed in interfaces since Java 8.
Related concept
Standard ACLs match source addresses.
- ✓
An interface can contain default methods
Why this is correct
Default methods provide a default implementation in interfaces.
Related concept
Standard ACLs match source addresses.
- ✗
An interface can have private fields
Why it's wrong here
Interface fields are implicitly public static final; private fields are not supported.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 1Z0-811 ACL questions on filtering logic and placement.
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FAQ
Questions learners often ask
What does this 1Z0-811 question test?
Object-Oriented Programming — This question tests Object-Oriented Programming — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: An interface can extend multiple interfaces — Options B, C, and D are true about interfaces in Java. An interface can extend multiple interfaces using the extends keyword. Since Java 8, interfaces can contain static methods (with body) and default methods. Option A is false because interfaces cannot be instantiated directly; they must be implemented by a class. Option E is false because interface fields are implicitly public static final; private fields are not permitted in interfaces (private methods are allowed since Java 9, but not fields).
What should I do if I get this 1Z0-811 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 1Z0-811 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Last reviewed: Jun 23, 2026
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