Quick Answer
The correct answer is that only the packages exported by com.example.lib are readable by com.example.app. This is because the Java module system enforces strong encapsulation: a module’s `module-info.java` must explicitly declare which packages are accessible to other modules using the `exports` directive, and any package not listed remains hidden. When a module like com.example.app declares `requires com.example.lib`, it gains access solely to those exported packages—unexported ones are completely invisible, even if they contain public classes. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this concept tests your understanding of module accessibility and is a frequent trap where candidates assume that requiring a module grants full read access to all its packages. A reliable memory tip is to think of `exports` as opening a door: if the door isn’t explicitly opened, the requiring module cannot see inside.
This 1Z0-829 practice question tests your understanding of java platform overview and packaging. 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.
Given two named modules where module com.example.app requires module com.example.lib, which packages of com.example.lib are readable by com.example.app?
All packages except those explicitly concealed
Why wrong: All non-exported packages are concealed regardless of explicit concealment.
All packages of com.example.lib
Why wrong: Non-exported packages are not readable.
Only the packages opened by com.example.lib
Why wrong: Open packages are for reflective access, not readability.
Only the packages exported by com.example.lib
A module reads only exported packages of required modules.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Only the packages exported by com.example.lib
Option D is correct because in the Java module system, a module can only access packages from another module that are explicitly exported using the `exports` directive in the module's `module-info.java` file. Since `com.example.app` requires `com.example.lib`, only the packages exported by `com.example.lib` are readable; unexported packages remain encapsulated and inaccessible.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
All packages except those explicitly concealed
Why it's wrong here
All non-exported packages are concealed regardless of explicit concealment.
All packages of com.example.lib
Why it's wrong here
Non-exported packages are not readable.
Only the packages opened by com.example.lib
Why it's wrong here
Open packages are for reflective access, not readability.
Only the packages exported by com.example.lib
Why this is correct
A module reads only exported packages of required modules.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse `opens` with `exports`, thinking that opening a package for reflection also makes it readable, but `opens` only grants reflective access and does not allow compile-time or direct read access.
Detailed technical explanation
Under the hood, the module system enforces encapsulation at the JVM level using module descriptors; the `exports` directive creates a public API boundary, while `opens` is specifically for reflective access (e.g., by frameworks like Hibernate or Spring). A real-world scenario: if `com.example.lib` exports `com.example.lib.api` but not `com.example.lib.internal`, then `com.example.app` can read only the `api` package, preventing accidental dependency on internal implementation details.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Java Platform Overview and Packaging — This question tests Java Platform Overview and Packaging — Read the scenario before looking for a memorised answer..
The correct answer is: Only the packages exported by com.example.lib — Option D is correct because in the Java module system, a module can only access packages from another module that are explicitly exported using the `exports` directive in the module's `module-info.java` file. Since `com.example.app` requires `com.example.lib`, only the packages exported by `com.example.lib` are readable; unexported packages remain encapsulated and inaccessible.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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