Java Development and Deployment Flashcards

Which tool introduced in Java 9+ creates a custom runtime image containing only the modules your application needs?

Answer: jlink

`jlink` assembles a custom runtime image from a set of modules, reducing the deployment footprint.

What is the purpose of the `jdeps` tool?

Answer: Analyze class and package-level dependencies of a JAR or class file

`jdeps` analyzes dependencies between packages and modules, helping identify which modules a class or JAR requires.

Which file in a JAR is responsible for specifying the Main-Class and other metadata?

Answer: META-INF/MANIFEST.MF

The `MANIFEST.MF` file inside `META-INF/` stores JAR metadata including `Main-Class`, `Class-Path`, and custom attributes.

When compiling with modules, which flag adds a module to the set of root modules without editing module-info.java?

Answer: --add-modules

`--add-modules` lets you include additional modules in the module graph without modifying module descriptors.

What is the default access level for a package inside a named module that does NOT use an `exports` directive?

Answer: The package is inaccessible to all other modules

In the module system, packages that are not explicitly exported are encapsulated and inaccessible to code in other modules.

Which command creates a `.jmod` file from a set of compiled classes and resources?

Answer: jmod create --class-path out mymodule.jmod

`jmod create` packages compiled classes, native libraries, and configuration files into a `.jmod` file used by `jlink`.

What does `--patch-module =` allow you to do at runtime?

Answer: Inject additional classes into a module without recompiling it

`--patch-module` overlays classes from a path into a named module, commonly used for testing or hot-patching.