The correct answer is to modify the code to use a public API from the standard library. This resolves the issue because Java 11 enforces strong encapsulation of internal APIs, such as those under the com.sun.* namespace, meaning they are no longer accessible by default at runtime even though they exist in the JDK. The NoClassDefFoundError occurs because the JRE hides these encapsulated classes, so replacing the internal API call with a supported public alternative—like java.nio.file.StandardWatchEventKinds—ensures the application runs on any compliant JRE. On the Oracle Java Foundations 1Z0-811 exam, this scenario tests your understanding of modular encapsulation and the shift away from internal APIs, a common trap where developers assume all standard library classes are accessible. A helpful memory tip: if it starts with com.sun., it’s sunblocked—stick to java.* or javax.* for safe, portable code.
1Z0-811 What is Java Practice Question
This 1Z0-811 practice question tests your understanding of what is java. 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.
A developer is tasked with deploying a Java application to a customer's server. The customer has only a JRE installed and no internet access. The application uses Java NIO and requires reading configuration files from the classpath. The application compiles and runs fine on the developer's machine which has JDK 11. However, when deploying the compiled JAR to the customer's JRE 11, it throws a 'NoClassDefFoundError' for a class that is part of the JDK's internal API (e.g., com.sun.nio.file.SensitivityWatchEventModifier). The developer is confused because the class is in the standard library. Which action should be taken to resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the code to use a public API from the standard library
Option A is correct. The issue is that the code uses an internal API that is encapsulated in Java 11. The correct solution is to replace it with a public API (e.g., using java.nio.file.StandardWatchEventKinds). Option B is incorrect because installing the JDK would expose the internal classes but is not a proper solution and may violate encapsulation. Option C is incorrect because the missing class is not a separate JAR; it's part of the JDK internal API. Option D is incorrect because recompiling with a lower target version does not change the use of internal APIs and may introduce other issues.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Recompile with a lower target version
Why it's wrong here
This does not address the use of internal APIs; they remain inaccessible.
✗
Add the missing JAR file to the classpath
Why it's wrong here
The class is not in a separate JAR; it is in the JDK's internal modules.
✓
Modify the code to use a public API from the standard library
Why this is correct
Internal APIs are not accessible; use public alternatives.
Related concept
Static NAT maps one inside address to one outside address.
✗
Install the JDK on the customer's server
Why it's wrong here
This would expose the internal class but is not a recommended solution; the JRE should suffice.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 1Z0-811 NAT questions on configuration and troubleshooting.
What is Java — This question tests What is Java — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Modify the code to use a public API from the standard library — Option A is correct. The issue is that the code uses an internal API that is encapsulated in Java 11. The correct solution is to replace it with a public API (e.g., using java.nio.file.StandardWatchEventKinds). Option B is incorrect because installing the JDK would expose the internal classes but is not a proper solution and may violate encapsulation. Option C is incorrect because the missing class is not a separate JAR; it's part of the JDK internal API. Option D is incorrect because recompiling with a lower target version does not change the use of internal APIs and may introduce other issues.
What should I do if I get this 1Z0-811 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 1Z0-811 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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