The correct answer is to add `requires com.fasterxml.jackson.databind` to the module-info.java of `com.bank.core`. This is because the Java module system enforces that each module must declare its own dependencies explicitly; a module cannot rely on transitive readability from another module to access types it uses directly. The `IllegalAccessError` occurs because `com.bank.core` internally calls Jackson classes, but its module-info.java lacks the `requires` directive, meaning the module does not read `com.fasterxml.jackson.databind` from its own perspective. On the 1Z0-829 exam, this scenario tests your understanding that explicit dependency declarations are mandatory for every module that directly uses another module’s types, regardless of what other modules require. A common trap is assuming that if module A requires module B, and module B requires module C, then module A automatically reads module C—this is false unless `requires transitive` is used. Memory tip: “Direct use demands direct requires—no freeloading on another module’s dependency.”
1Z0-829 Java Platform Overview and Packaging Practice Question
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.
You are a software architect at a financial firm. Your team is developing a modular Java 17 application that comprises several modules: 'com.bank.core' (provides core banking services), 'com.bank.web' (REST API), and 'com.bank.persistence' (database access). The application uses the 'java.sql' module for JDBC and 'java.logging' for logging. The team uses Maven for dependency management. The application has an external dependency on the 'com.fasterxml.jackson.databind' library (Jackson) for JSON processing, which is provided as a non-modular jar. The Jackson jar is placed on the module path. The application modules are all named modules with module-info files. At runtime, the 'com.bank.web' module requires 'com.bank.core' and 'com.fasterxml.jackson.databind' (the automatic module). The 'com.bank.core' module requires 'java.sql' and 'java.logging'. When the application runs, it throws an 'IllegalAccessError' indicating that the module 'com.bank.core' tries to access a class from 'com.fasterxml.jackson.databind' but the module does not read it. Yet, 'com.bank.web' is the only module that explicitly requires Jackson. What is the most likely cause and the correct resolution?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add 'requires com.fasterxml.jackson.databind' to the module-info.java of 'com.bank.core' because it uses Jackson classes directly.
Option B is correct because the error indicates that 'com.bank.core' directly uses classes from 'com.fasterxml.jackson.databind', but its module-info.java does not include a 'requires com.fasterxml.jackson.databind' directive. In the Java module system, a module can only access types from another module if it explicitly reads that module. Since 'com.bank.core' needs Jackson classes at runtime, it must declare the dependency itself, even if another module ('com.bank.web') also requires it.
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.
✗
Convert all application modules to unnamed modules by removing module-info files.
Why it's wrong here
This abandons modularity, making the application harder to maintain and deploy.
✓
Add 'requires com.fasterxml.jackson.databind' to the module-info.java of 'com.bank.core' because it uses Jackson classes directly.
Why this is correct
Direct use requires a requires directive; this resolves the readability chain.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Place the Jackson jar on the classpath instead of the module path.
Why it's wrong here
Then no named module can read it without --add-reads; also, unnamed modules are not visible to named modules by default.
✗
Use jlink to create a custom runtime image including all modules and the Jackson jar.
Why it's wrong here
jlink would not fix the readability; the missing requires directive remains.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume transitive dependencies are automatically resolved by the module system, but in Java modules, each module must explicitly declare its own 'requires' for any module it directly uses, even if another module already requires it.
Detailed technical explanation
How to think about this question
The Java module system enforces readability at compile time and runtime: a module can only access types from another module if it has a 'requires' directive for that module. Automatic modules (like Jackson from a non-modular jar) are treated as modules with exported packages, but they still require explicit 'requires' in the consuming module's module-info. This prevents accidental transitive dependencies and ensures that each module declares its own dependencies, which is critical for maintainability in large applications.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Java Platform Overview and Packaging — This question tests Java Platform Overview and Packaging — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add 'requires com.fasterxml.jackson.databind' to the module-info.java of 'com.bank.core' because it uses Jackson classes directly. — Option B is correct because the error indicates that 'com.bank.core' directly uses classes from 'com.fasterxml.jackson.databind', but its module-info.java does not include a 'requires com.fasterxml.jackson.databind' directive. In the Java module system, a module can only access types from another module if it explicitly reads that module. Since 'com.bank.core' needs Jackson classes at runtime, it must declare the dependency itself, even if another module ('com.bank.web') also requires it.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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