Quick Answer
The answer is the `--main-class` option. This is correct because when creating an executable JAR file, the Java launcher needs to know which class contains the `public static void main(String[])` entry point; the `--main-class` flag (or its older shorthand `-e`) tells the `jar` command to embed that fully qualified class name into the `Main-Class` header of the `META-INF/MANIFEST.MF` file, which the runtime reads at launch. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your familiarity with the modern `jar` command syntax introduced in Java 9, often appearing as a straightforward recall item. A common trap is confusing `--main-class` with `--module-version` or forgetting that the older `-e` flag is still accepted but not the preferred answer for the current exam. Memory tip: think "main-class" as in "main entry class"—the hyphen connects the two words that define the JAR's starting point.
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 wants to create an executable JAR file. Which jar command option is used to specify the main class?
--main-class
--main-class specifies the main class for an executable JAR.
--class-path
Why wrong: --class-path sets the class path for the JAR, not the main class.
--module-version
Why wrong: --module-version sets the module version, not the main class.
--create
Why wrong: --create is used to create a new JAR file, not set the main class.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
--main-class
Option A is correct because the `--main-class` option (or `-e` in older syntax) specifies the fully qualified name of the class containing the `public static void main(String[])` method when creating an executable JAR with the `jar` command. This entry is stored in the JAR's `META-INF/MANIFEST.MF` file under the `Main-Class` header, which the Java launcher reads to determine the entry point.
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.
--main-class
Why this is correct
--main-class specifies the main class for an executable JAR.
Related concept
Read the scenario before looking for a memorised answer.
--class-path
Why it's wrong here
--class-path sets the class path for the JAR, not the main class.
--module-version
Why it's wrong here
--module-version sets the module version, not the main class.
--create
Why it's wrong here
--create is used to create a new JAR file, not set the main class.
Common exam traps
The trap here is that candidates often confuse `--main-class` with `--class-path` or think `--create` alone makes the JAR executable, but `--create` only builds the archive without setting an entry point.
Detailed technical explanation
Under the hood, the `jar` command writes the `Main-Class` attribute into the manifest file. When the JAR is launched with `java -jar`, the launcher parses the manifest, loads the specified class, and invokes its `main` method. A subtle behavior is that if the main class is not in the JAR but on the classpath, the launcher will throw a `ClassNotFoundException`. In real-world scenarios, forgetting `--main-class` results in a JAR that can be used as a library but cannot be executed directly.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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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: --main-class — Option A is correct because the `--main-class` option (or `-e` in older syntax) specifies the fully qualified name of the class containing the `public static void main(String[])` method when creating an executable JAR with the `jar` command. This entry is stored in the JAR's `META-INF/MANIFEST.MF` file under the `Main-Class` header, which the Java launcher reads to determine the entry point.
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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