1Z0-811 Java Development and Deployment

Question 1

What is the purpose of the "module-info.java" file in a Java module?

Accepted Answer

To specify the modules that the current module depends on and the packages it exports

Answer

The `module-info.java` file is the module descriptor in the Java Platform Module System (JPMS). It explicitly defines a module's name, declares its dependencies on other modules using `requires`, and specifies which of its packages are accessible to other modules using `exports`. This file is crucial for enforcing strong encapsulation and reliable configuration in modular applications.

Question 2

How does Java handle memory management and garbage collection?

Accepted Answer

By using a garbage collector to automatically reclaim memory from objects that are no longer in use

Answer

Java handles memory management automatically through a process called garbage collection. The garbage collector continuously monitors memory and reclaims space occupied by objects that are no longer referenced or reachable by the running application. This frees developers from manual memory allocation and deallocation, reducing memory leaks and improving application stability.

Question 3

What does the "javac" command do?

Accepted Answer

It compiles Java source code into bytecode

Answer

The `javac` command is the Java compiler. Its primary function is to translate Java source code files (with a `.java` extension) into Java bytecode files (with a `.class` extension). These bytecode files are then executed by the Java Virtual Machine (JVM).

Question 4

What is a JAR file in Java?

Accepted Answer

A compressed file format used to bundle multiple Java class files and associated metadata into a single archive

Answer

A JAR (Java Archive) file is a compressed file format, based on the ZIP format, used to bundle multiple Java class files, associated metadata, and resources (like images or configuration files) into a single archive. This makes it convenient for distributing and deploying Java applications and libraries as a single unit.

Question 5

What is the -classpath option used for when running the java command?

Accepted Answer

To set the path for finding Java libraries and classes during runtime

Answer

When running the `java` command, the `-classpath` (or `-cp`) option is used to specify the path where the Java Virtual Machine (JVM) should look for user-defined classes and packages. This path includes directories containing `.class` files and JAR files, ensuring that the JVM can locate all necessary components for the application to execute correctly at runtime.

(1Z0-811) Oracle Java SE11 Programmer Practice Test

(1Z0-811) Oracle Java SE11 Programmer Practice Test

1Z0-811 Java Development and Deployment