The answer is the `--module` option. For a modular application where the main class is already declared in `module-info.java`, jpackage requires the `--module` option to specify the module name and the fully qualified main class, typically in the format `--module com.example/com.example.Main`. This is because jpackage leverages the Java module system to resolve the entry point directly from the module descriptor, rather than relying on a classpath or JAR manifest. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of how jpackage interacts with modular applications, often appearing as a distractor where candidates mistakenly choose `--main-jar` or `--class`. A common trap is assuming you must repeat the main class with `--main-class` even when it is already in `module-info`, but the `--module` option alone handles both the module and its declared entry point. Memory tip: think "module first" — for modular apps, `--module` is the only key that unlocks the entry point.
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.
A developer creates a Java application that uses the new 'jpackage' tool to create an installer for Windows. The application is modular and has a main class declared in module-info. Which option is required to specify the main class when using jpackage?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
--module
For a modular application with a main class declared in module-info, jpackage requires the `--module` option to specify the module name and, optionally, the main class (e.g., `--module com.example/com.example.Main`). This is because jpackage uses the module system to resolve the entry point, not a classpath or JAR-based approach.
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.
✗
-classpath
Why it's wrong here
classpath is not used with jpackage; the tool uses module path.
✗
--module-path
Why it's wrong here
--module-path specifies locations of modules, but does not identify the main class.
✗
--main-jar
Why it's wrong here
--main-jar is used for non-modular applications packaged as a jar with a Main-Class attribute.
✓
--module
Why this is correct
For modular applications, jpackage uses --module to specify the main module, and the application's main class is derived from the module descriptor.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse `--module` with `--module-path` or `--main-jar`, mistakenly thinking the main class must be specified via a JAR or classpath even when the module system already declares it.
Detailed technical explanation
How to think about this question
Under the hood, jpackage invokes `jlink` and `jmod` to create a custom runtime image, and for modular applications, it reads the module descriptor (module-info.class) to find the main class. If the main class is not specified in the `--module` option, jpackage will use the one declared in module-info; if neither is present, it fails. This ensures the resulting installer has a correct entry point without relying on a manifest file.
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: --module — For a modular application with a main class declared in module-info, jpackage requires the `--module` option to specify the module name and, optionally, the main class (e.g., `--module com.example/com.example.Main`). This is because jpackage uses the module system to resolve the entry point, not a classpath or JAR-based approach.
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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Question Discussion
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