1Z0-811 Java Development and Deployment 2

Question 1

Which command compiles a Java source file named `Hello.java` and places the output in a directory called `out`?

Accepted Answer

javac -d out Hello.java

Answer

The `javac -d <dir>` option specifies the destination directory for compiled `.class` files.

Question 2

What is the result of running `java -jar app.jar` when the manifest file has no `Main-Class` attribute?

Accepted Answer

An error is thrown indicating no main manifest attribute

Answer

Without a `Main-Class` attribute in MANIFEST.MF, the JVM cannot determine the entry point and reports an error.

Question 3

Which module directive is used to allow reflective access to all packages in a module by a specific other module?

Accepted Answer

opens <package> to <module>

Answer

The `opens` directive grants reflective access (e.g., for frameworks) while `exports` only grants compile/run-time API access.

Question 4

What does the `javap -c` command display for a `.class` file?

Accepted Answer

Disassembled JVM bytecode instructions

Answer

`javap -c` disassembles and prints the bytecode instructions for each method in the class file.

Question 5

In a multi-release JAR, where should Java 11-specific class files be placed?

Accepted Answer

META-INF/versions/11/

Answer

Multi-release JARs place version-specific classes under `META-INF/versions/<N>/` where N is the Java version.

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