1Z0-811 What is Java Practice Test 2 — 15 Questions

Question 1

A junior developer installs the JDK on Windows and configures the PATH environment variable. In a new Command Prompt, typing java -version prints the runtime version, but typing javac -version returns 'javac is not recognized as an internal or external command.' The JDK was installed to C:\Program Files\Java\jdk-21 and the PATH currently contains only C:\Program Files\Java\jdk-21\bin. Which action most directly resolves the problem?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Verify that C:\Program Files\Java\jdk-21\bin actually contains javac.exe and that the PATH entry is correct, then open a new Command Prompt.. Compiling requires the javac tool, which is shipped in the JDK's bin directory. The runtime java launcher and the compiler javac live side by side there, so if java works but javac does not, the bin directory on PATH is either wrong, incomplete, or the shell predates the change. Verifying the file and restarting the terminal is the direct fix.

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Install a separate JRE and point JAVA_HOME to that JRE installation.

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Set the CLASSPATH environment variable to include the JDK installation directory.

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Add C:\Program Files\Java\jdk-21\lib to the PATH variable.

Question 2

A team is designing a Java application that needs to run on different operating systems without modification. Which Java feature makes this possible?

Accepted Answer

The Java Virtual Machine. The Java Virtual Machine (JVM) is the key enabler of Java's 'write once, run anywhere' capability. When you compile Java source code, the Java compiler produces bytecode, which is platform-independent. This bytecode is then executed by the JVM, which is implemented specifically for each operating system (Windows, Linux, macOS, etc.), translating the bytecode into native machine instructions. Therefore, the same compiled .class file can run on any OS that has a compatible JVM, without requiring any modifications to the application code.

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Just-in-time compilation

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Garbage collection

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The Java compiler

Question 3

Which TWO statements correctly describe the Java language? (Choose two.)

Accepted Answer

Java supports object-oriented programming.. Java is fundamentally an object-oriented programming language that supports encapsulation, inheritance, and polymorphism. Java's design revolves around classes and objects, and all code must be written inside a class, making OOP a core principle of the language.

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Java supports multiple inheritance of implementation.

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Java supports operator overloading.

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Java supports multiple inheritance of classes.

Question 4

A developer runs the command shown in the exhibit. The developer wants to ensure the application uses the latest available language features. Which action should the developer take?

Accepted Answer

Download and install a newer version of the JDK.. The latest available language features (e.g., pattern matching, sealed classes, records) are tied to the JDK version. Downloading and installing a newer JDK provides both the compiler (javac) and runtime (JVM) that support those features. Simply upgrading the JVM (Option D) or using -source/-target flags (Option C) does not enable new language syntax in the compiler if the JDK itself is outdated.

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Enable lambda expressions by setting the -enable-lambdas flag.

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Use the -source and -target flags to compile for a newer version.

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Upgrade the JVM to the latest version.

Question 5

Arrange the steps to compile and run a Java program from the command line in the correct order.

Accepted Answer

Write code, Open terminal, Navigate to file directory, Compile with javac, Run with java. The correct order is to first write the code, then open terminal, navigate to the file location, compile with javac, and run with java.

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Write code, Open terminal, Compile with javac, Navigate to file directory, Run with java

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Open terminal, Write code, Navigate to file directory, Compile with javac, Run with java

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Write code, Open terminal, Navigate to file directory, Run with java, Compile with javac

Question 6

Arrange the steps to overload a method in Java in the correct order.

Accepted Answer

Define a method, then define another method with the same name but different parameters, then ensure the method signatures are unique, then call the method with arguments that match one of the signatures.. First define one method, then define another with same name but different parameters, ensure unique signatures, and then call with matching arguments.

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Define a method, then ensure the method signatures are unique, then define another method with the same name but different parameters, then call the method with arguments.

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Define another method with the same name but different parameters, then define a method, then ensure unique signatures, then call the method.

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Call the method with arguments, then define a method, then define another method with the same name but different parameters, then ensure unique signatures.

Question 7

Match each Java term to its correct definition.

Accepted Answer

JDK: Software development kit that includes tools for compiling, debugging, and running Java programs. Correct matches: JDK is the development kit; JRE is the runtime; JVM executes bytecode; bytecode is the intermediate format. Common confusions: mixing JDK and JRE or JVM with JDK.

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JDK: Runtime environment that includes the JVM and core libraries required to run Java programs

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JVM: Software development kit that includes tools for compiling, debugging, and running Java programs

Question 8

A developer says Java is platform-independent because of the JVM. Which statement best explains this?

Accepted Answer

Java source code is compiled into bytecode, which runs on the Java Virtual Machine (JVM).. Java achieves platform independence through a two-step compilation model: javac compiles source code into platform-neutral bytecode (.class files), and the JVM on each platform interprets or JIT-compiles that bytecode into native instructions. Because the bytecode is the same everywhere and only the JVM is platform-specific, the same compiled artifact runs on Windows, Linux, or macOS without recompilation.

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Java source code is compiled directly into native machine code for each platform.

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The JVM is written in platform-independent code, allowing it to run anywhere.

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Java uses an interpreter only, so the source code is interpreted directly on any platform.

Question 9

A company is developing a security-sensitive banking application. Which Java feature most directly enhances security?

Accepted Answer

Bytecode verification. Bytecode verification is the Java feature that most directly enhances security because it ensures that compiled Java bytecode adheres to the JVM's safety rules before execution, preventing malformed or malicious bytecode from compromising the runtime. The verifier checks type safety, stack integrity, and access control, blocking many low-level attacks.

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Automatic garbage collection

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Platform independence via bytecode

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Built-in multithreading support

Question 10

A team deploys a Java application and observes frequent Full GC pauses. Which garbage collector is designed to minimize pause times?

Accepted Answer

Garbage-First (G1GC) (-XX:+UseG1GC). G1GC is designed to minimize pause times by dividing the heap into regions and prioritizing the collection of regions with the most garbage (hence 'Garbage-First'). It allows the user to specify a target pause time via -XX:MaxGCPauseMillis, and it performs incremental collections, often avoiding full heap compactions. This makes it suitable for applications where low latency is critical, such as the one described with frequent Full GC pauses.

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Concurrent Mark Sweep (CMS) (-XX:+UseConcMarkSweepGC)

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Serial GC (-XX:+UseSerialGC)

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Parallel GC (-XX:+UseParallelGC)

Question 11

What is the primary role of the Java Development Kit (JDK) compared to the JRE?

Accepted Answer

JDK includes compilers and tools for developing Java applications.. The JDK (Java Development Kit) is a software development environment used for developing Java applications. It includes the JRE (Java Runtime Environment) plus development tools such as the Java compiler (javac), debugger, and other utilities. In contrast, the JRE provides only the runtime environment needed to run Java applications. Therefore, option D is correct because the JDK includes compilers and tools for development. Option A is incorrect because the JDK provides far more than just a debugger and profiler; it includes the compiler and other essential tools. Option B is incorrect because the JDK includes the JRE, not the other way around. Option C is incorrect because the JRE is required to run Java applications, while the JDK is needed for development; the JDK is not required to run applications.

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JDK provides only a debugger and profiler.

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JRE includes the JDK and additional libraries.

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JDK is required to run Java applications, whereas JRE is not.

Question 12

In the Java memory model, where are primitive local variables declared inside a method stored?

Accepted Answer

Stack. In the Java memory model, primitive local variables declared inside a method are stored on the stack. Each thread has its own stack, and each method invocation creates a stack frame that holds local variables, including primitives and object references. This is distinct from objects themselves, which are allocated on the heap.

Answer

Heap

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Native method area

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Method area

Question 13

What is the primary purpose of Java bytecode?

Accepted Answer

To be executed by the Java Virtual Machine on any platform. Java bytecode is designed to be executed by the Java Virtual Machine (JVM), which interprets or compiles it to native code for the underlying platform, enabling platform independence. Option B is incorrect because bytecode is an intermediate representation that is compiled or interpreted at runtime, not compiled once into native code for reuse across platforms. Option C is incorrect because bytecode is not human-readable source code; it is a binary format. Option D is incorrect because bytecode cannot be directly executed by the operating system; it requires the JVM to run.

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To be compiled into native code once and reused

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To be human-readable source code

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To be directly executed by the operating system

Question 14

During execution, the JVM uses Just-In-Time (JIT) compilation. What is its primary benefit?

Accepted Answer

Improves execution speed by compiling frequently used bytecode to native code.. JIT compilation improves execution speed by compiling frequently used bytecode into native machine code at runtime. Option A is incorrect because JIT does not translate bytecode into an intermediate language; it compiles to native code. Option C is incorrect because JIT compiles bytecode, not source code. Option D is incorrect because JIT's primary purpose is performance, not security.

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Translates bytecode into an intermediate language for interpretation.

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Converts Java source code directly into bytecode.

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Enhances security by verifying bytecode integrity.

Question 15

Which TWO statements are true about the Java programming language?

Accepted Answer

It is a strongly-typed language.. Option C is correct because Java is a statically and strongly-typed language: every variable and expression has a type known at compile time, and the compiler enforces type compatibility, rejecting implicit conversions that would lose precision (for example, assigning a double to an int without a cast). Option E is correct because Java's runtime (the JVM) performs automatic memory management via garbage collection, reclaiming heap objects that are no longer reachable so developers do not manually free memory. Option A is wrong because Java is fundamentally object-oriented (classes, inheritance, polymorphism), not purely procedural. Option B is wrong because Java deliberately omits direct pointer arithmetic and manipulation; references are managed by the JVM for safety and portability. Option D is wrong because Java permits only single inheritance of classes (a class extends exactly one superclass), though it does allow multiple inheritance of interfaces.

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It is a purely procedural language.

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It supports direct pointer manipulation for memory access.

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It allows multiple inheritance of classes.