1Z0-829 Java Platform Overview and Packaging Practice Test 3 — 15 Questions

Question 1

A developer runs the above jdeps command on app.jar. Which statement about the dependencies is correct?

Accepted Answer

The app.jar depends on java.base implicitly.. Every Java module automatically has an implicit dependency on the `java.base` module, which is always resolved by the module system. The `jdeps` command analyzes dependencies, and even if no explicit `requires java.base` is declared, the module system adds it implicitly. This is a fundamental rule of the Java Platform Module System (JPMS) as defined in JSR 376.

Answer

The app.jar has a direct dependency on the class com.thirdparty.util.

Answer

The modular dependency com.thirdparty.helper is not required because it is modular.

Answer

The dependencies on com.thirdparty.util and com.thirdparty.helper are on the module path.

Question 2

Given the module descriptor for com.example.payment:

module com.example.payment {
    exports com.example.payment;
    // does not require com.example.store
}

And the Main class is in the unnamed module (on the classpath). The invocation is:

java --add-modules com.example.store --module-path mods -cp classes com.example.Main

What will happen?

Accepted Answer

The application runs successfully because com.example.store is added with --add-modules, and its exported packages are available.. The `--add-modules com.example.store` directive explicitly adds the module `com.example.store` to the set of root modules at startup, making its exported packages available to the unnamed module (or to modules that do not otherwise require it). Since the `Main` class is in the unnamed module (not in a named module), it can access the exported packages of `com.example.store` without a `requires` clause. This is the intended behavior of `--add-modules` for resolving modules that are not automatically resolved.

Answer

The application throws NoClassDefFoundError because the Main class is in a different module.

Answer

The application runs successfully because com.example.store is on the module path.

Answer

The application throws ModuleNotFoundException because com.example.store is not required by com.example.payment.

Question 3

A developer runs `java --list-modules` and sees the above output on a standard JDK installation. What does this output represent?

Accepted Answer

The set of modules available in the current JDK.. The `java --list-modules` command outputs the names of all observable modules that are part of the current JDK installation. This includes all platform modules (e.g., `java.base`, `java.sql`, `jdk.compiler`) that are available for use, regardless of whether they are currently required or loaded by an application. Option C correctly identifies this as the set of modules available in the current JDK.

Answer

The modules that are part of the java.base module.

Answer

The modules that are required by the current application.

Answer

The modules that are currently loaded by the JVM.

Question 4

A developer has created a modular Java application. They want to distribute a minimal runtime image containing only the required modules. Which tool should they use?

Accepted Answer

jlink. B is correct because `jlink` is the Java tool specifically designed to assemble and optimize a minimal runtime image containing only the modules explicitly required by the application and its transitive dependencies. It links the specified modules and their dependencies into a custom JRE that excludes unused modules, reducing footprint for distribution.

Answer

javac

Answer

jar

Answer

jpackage

Question 5

In a modular Java application, where does the module declaration file typically reside?

Accepted Answer

In a file named module-info.java at the root of the module's source tree. The module declaration for a modular Java application must be placed in a file named `module-info.java` at the root of the module's source tree. This file is then compiled into `module-info.class` and placed in the output directory, but the source declaration resides in the source tree root as per the Java Platform Module System (JPMS) specification.

Answer

In a file named module-info.class in the output directory

Answer

In the META-INF directory

Answer

In the root of the source directory

Question 6

A developer wants to create an executable JAR file. Which jar command option is used to specify the main class?

Accepted Answer

--main-class. 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.

Answer

--class-path

Answer

--module-version

Answer

--create

Question 7

A developer places a non-modular JAR file on the module path. What type of module does this JAR become?

Accepted Answer

Automatic module. When a non-modular JAR is placed on the module path, the Java module system automatically derives a module from it, known as an automatic module. This is because the JAR lacks a module-info.class, so the system infers a module name from the JAR filename (e.g., using the Main-Class attribute or the JAR's name) and exports all packages, giving it access to all other modules. Option C is correct because the JAR becomes an automatic module, not a named or unnamed module.

Answer

Open module

Answer

Named module

Answer

Unnamed module

Question 8

A company wants to distribute a Java desktop application with a bundled JRE for end users who may not have Java installed. Which tool should they use?

Accepted Answer

jpackage. jpackage is the correct tool because it is specifically designed to package a Java application along with a bundled JRE into a native installer (e.g., .exe, .dmg, .deb) for distribution to end users who may not have Java installed. It uses the jlink tool internally to create a custom runtime image and then wraps it with platform-specific packaging tools, ensuring the application runs independently of any pre-installed JRE.

Answer

jlink

Answer

jar

Answer

jmod

Question 9

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?

Accepted Answer

Only the packages exported by com.example.lib. 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.

Answer

All packages except those explicitly concealed

Answer

All packages of com.example.lib

Answer

Only the packages opened by com.example.lib

Question 10

A team has a multi-release JAR that supports both Java 11 and Java 17. They want to ensure that when running on Java 17, the version-specific classes in META-INF/versions/17 are used. Which condition must be true?

Accepted Answer

The manifest must contain 'Multi-Release: true'. The Java runtime checks for the `Multi-Release: true` entry in the JAR's manifest file to enable multi-release JAR functionality. Without this manifest attribute, the JVM ignores versioned directories under `META-INF/versions/` and uses only the root classes, even if the JAR was compiled with `--multi-release 17`.

Answer

The JAR must have a module-info.class in the root

Answer

The JAR must be placed on the module path

Answer

The JAR must be created using the --multi-release 17 option

Question 11

A developer is migrating a classpath-based application to modules. They have two JARs on the classpath that both contain a package with the same name, com.example.util. When they move both JARs to the module path, they encounter a module resolution error. What is the most likely cause?

Accepted Answer

Named modules cannot have split packages. In the Java module system, a package can be defined in at most one module on the module path. When both JARs contain com.example.util, moving them to the module path creates a split package, which is illegal for named modules. The module system enforces this to ensure reliable configuration and encapsulation, resulting in a module resolution error.

Answer

The --add-exports option is missing

Answer

The JARs need to be merged into one module

Answer

Automatic modules cannot have split packages

Question 12

A company uses jlink to create a custom runtime image. They want to reduce the image size by removing debug information. Which jlink option or plugin should they use?

Accepted Answer

--strip-debug. The `--strip-debug` option in jlink removes debug information from the custom runtime image, including line numbers, local variable tables, and source file references, which significantly reduces the image size. This is the correct option for stripping debug information, as it directly targets the removal of debugging metadata from the generated image.

Answer

--compress=2

Answer

--no-header-files

Answer

--bind-services

Question 13

Which TWO statements about Java module types are true?

Accepted Answer

An automatic module exports all its packages.. The Java module system automatically exports all packages of an automatic module, making them accessible to other modules without explicit export declarations. This is a key characteristic of automatic modules, which are created from JAR files placed on the module path without a module-info.java file.

Answer

An automatic module can access all packages of named modules without explicit requires.

Answer

The unnamed module can read only the java.base module.

Answer

The unnamed module is a named module.

Question 14

Which THREE statements about the jpackage tool are true?

Accepted Answer

jpackage can create native installers for Windows, macOS, and Linux.. The jpackage tool is designed to create native installers for Windows (e.g., .exe/.msi), macOS (e.g., .dmg), and Linux (e.g., .deb/.rpm). This is a core feature of jpackage, which replaces the older Java Packager and allows developers to distribute self-contained applications with platform-specific packaging formats.

Answer

jpackage requires an existing JRE to create a runtime image.

Answer

jpackage uses the Java Packager library.

Question 15

Which TWO statements about module descriptors are true?

Accepted Answer

A module descriptor can use the opens keyword to enable deep reflection on specific packages.. The `opens` keyword in a module descriptor (module-info.java) allows deep reflection (access to private members) on specific packages at runtime, which is necessary for frameworks like Hibernate or JPA that rely on reflection. Option E is correct because the `transitive` keyword is used only within `requires` directives to indicate that any module that requires the current module also implicitly requires the specified module.

Answer

A module descriptor can use the provides keyword to declare that it uses a service.

Answer

A module descriptor must require the java.base module explicitly.

Answer

A module descriptor can specify which packages are exported with the export keyword.