1Z0-819 Modular Development & Deployment Practices 3

Question 1

What is the unnamed module in the Java Platform Module System?

Accepted Answer

A virtual module that contains all classes loaded from the class path

Answer

The unnamed module is a synthetic module that groups all types loaded from the class path, enabling backward compatibility with pre-module code.

Question 2

A `module-info.java` contains `opens com.example.impl to com.framework;`. What does this enable?

Accepted Answer

Deep reflection into com.example.impl exclusively by com.framework at runtime

Answer

A qualified `opens` grants the specified module the ability to use deep reflection (including private members) on the opened package at runtime.

Question 3

Which file format does `jmod` create, and what is it primarily used for?

Accepted Answer

A .jmod file used for packaging modules for jlink and distribution

Answer

`jmod` creates `.jmod` files that can bundle native code, config files, and legal notices alongside classes — primarily consumed by `jlink` to build runtime images.

Question 4

How does the Java module system handle split packages (the same package name in two named modules)?

Accepted Answer

It throws an error at module resolution time — split packages are not allowed between named modules

Answer

Split packages between two named modules are illegal; the module system rejects them during resolution with a `LayerInstantiationException` or startup error.

Question 5

Which `java` flag prints a module's descriptor including its requires, exports, and provides declarations?

Accepted Answer

--describe-module

Answer

`--describe-module <module-name>` prints the full module descriptor showing all directives declared in its `module-info`.

(1Z0-819) Oracle Java SE 11 Developer Practice Test

(1Z0-819) Oracle Java SE 11 Developer Practice Test

1Z0-819 Modular Development & Deployment Practices 3