What Is JVM (Java Virtual Machine)

This section describes what is JVM (Java Virtual Machine).

What Is JVM (Java Virtual Machine)? The Java Virtual Machine is an abstract computing machine that can execute a program written in its machine instruction set, called bytecode.

Like any other virtual machine, the JVM must be implemented on a real computer machine in order to actually run any programs written in the JVM bytecode.

We also need a higher level language like Java and a compiler, so that we create programs quickly in Java and compile it into JVM bytecode. Because writing large programs directly in JVM bytecode is very difficult.

Putting the above together, here is the process of writing and running programs on a JVM:

Here is a simple diagram that illustrates the process of writing and running programs on a JVM:

JVM Programming Process
JVM Programming Process

Last update: 2018.

Table of Contents

 About This Book

JVM (Java Virtual Machine) Specification

What Is JVM (Java Virtual Machine)

 What Is JVM Specfication

 JVM Architectures and Components

 Implementations of JVM Specfication

 Java HotSpot VM - JVM by Oracle/Sun

 java.lang.Runtime Class - The JVM Instance

 java.lang.System Class - The Operating System

 ClassLoader Class - Class Loaders

 Class Class - Class Reflections

 JVM Runtime Data Areas

 JVM Stack, Frame and Stack Overflow

 Thread Testing Program and Result

 CPU Impact of Multi-Thread Applications

 I/O Impact of Multi-Thread Applications

 CDS (Class Data Sharing)

 Micro Benchmark Runner and JVM Options

 Micro Benchmark Tests on "int" Operations

 Micro Benchmark Tests on "long" Operations

 Micro Benchmark Tests in JIT Compilation Mode

 Micro Benchmark Tests on "float" and "double" Operations

 JRockit JVM 28.2.7 by Oracle Corporation

 Outdated Tutorials

 References

 Full Version in PDF/EPUB