Core Java Interview Questions Set 1

Questions and Answers

What characteristics make Java a platform-independent programming language?

Java is compiled into machine code.

Java requires hardware-specific compilers.

Java uses the Java Virtual Machine. (correct)

Java is an interpreted language only.

Which of the following best describes the role of the Java Virtual Machine (JVM)?

It manages memory for Java applications.

It translates Java bytecode into human-readable code.

It compiles Java code into machine code.

It provides a runtime environment for executing Java programs. (correct)

What is the primary function of the Java Runtime Environment (JRE)?

To provide a development environment for Java applications.

To execute Java bytecode on the host machine. (correct)

To manage various Java libraries and dependencies.

To compile Java programs into bytecode.

Which of the following statements about JDK, JRE, and JVM is true?

JVM is a runtime instance created when Java code is executed. Signup and view all the answers

Who developed the Java programming language?

James Gosling Signup and view all the answers

Which of the following is NOT a feature of the Java programming language?

Machine-specific Signup and view all the answers

What is the main purpose of compiling Java code into bytecode?

To allow the Java program to run on any hardware platform. Signup and view all the answers

What happens when a Java program is executed?

A Java Virtual Machine creates a runtime instance for execution. Signup and view all the answers

What is the primary function of the Just-In-Time (JIT) compiler in Java?

To compile bytecode for faster execution based on functionality. Signup and view all the answers

Which components are included in the Java Development Kit (JDK)?

JRE and development tools. Signup and view all the answers

What characterizes the bytecode generated by Java programs?

It is an intermediate language that can be executed on any machine. Signup and view all the answers

What is the role of a classloader in Java?

To load class files into memory at runtime. Signup and view all the answers

What result occurs if no arguments are provided at the command line for the main() method?

The String array will be empty. Signup and view all the answers

What types of platforms does Java provide?

Only software-based platforms. Signup and view all the answers

Which of the following statements about source file names in Java is true?

Files must end with .java and can be named anything valid. Signup and view all the answers

Which of the following best describes the nature of JVM's memory area allocation?

JVM allocates different types of memory areas for various purposes. Signup and view all the answers

Study Notes

Core Java Interview Questions Overview

A collection of 300 core Java interview questions, providing a 90% assurance of frequently asked questions in interviews.
Categories include Basics, OOP, String Handling, Multithreading, Collections, and JDBC.

Java Fundamentals

Java is a high-level, object-oriented, secure, and robust programming language that is platform-independent and multithreaded.
Developed by James Gosling in June 1991, it includes its own Java Runtime Environment (JRE) and Application Programming Interface (API).

Key Differences

Differences between C++ and Java include syntax, memory management, and inheritance models.

Java Language Features

Java offers features such as portability, automatic memory management (garbage collection), and strong type checking.

Java Virtual Machine (JVM)

JVM is a runtime engine that allows execution of Java bytecode, acting as an abstract machine.
Compiles Java source code to bytecode, which is platform-independent.
JVM has specifications, implementations, and instances, with physical existence provided by JRE.

Java Development Kit (JDK) and Java Runtime Environment (JRE)

JRE is the implementation of JVM, containing libraries and files for running Java applications.
JDK is a software development environment that includes JRE as well as development tools to create Java applications.

JVM Memory Areas

JVM allocates various types of memory areas for its execution, enhancing performance and management.

Just-In-Time (JIT) Compiler

JIT compiler enhances performance by compiling bytecode into native machine code at runtime, reducing compilation time.

Platform Definition

In programming, a platform refers to the hardware or software underlying the execution of software. Java is classified as a software-based platform.

Java's Portability

Java's "write once, run anywhere" capability stems from bytecode, which is an intermediate representation that can run on any machine with a JVM.

Classloader

A subsystem of JVM that loads class files into memory for execution; includes built-in classloaders.

Source File Naming Convention

Java source files must end with a .java extension, and can be compiled with javac and executed with java.

Command Line Arguments

If no arguments are passed to the main() method, the String array is initialized as empty, not null.

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Description

This quiz presents a set of 300 core Java interview questions that aim to prepare you for job interviews. With a high assurance of 90% relevance, each question is short and categorized, ensuring clear and concise answers. Perfect for anyone looking to strengthen their Java knowledge for upcoming interviews.