JAVA TUTORIAL

Java Intro Java Features Java vs C++ Java Simple Program Java Applet vs Application JVM,JDK or JRE Java Keywords Java Variables Java Literals Java Separators Java Datatypes Java Operators Java Statements Java Array Java String

CONTROL STATEMENTS

Java If-else Java While Loop Java Do-While Loop Java For Loop Java For-each Loop Java Switch Java Break/Continue

JAVA METHODS

Java Method Java Overloading Java Overriding

JAVA CLASSES

Java OOPs Java Classes/Objects Java Inheritance Java Polymorphism Java Encapsulation Java Abstraction Java Modifiers Java Constructors Java Interface Java static keyword Java this keyword

Difference between JVM, JDK and JRE

JVM

Java Virtual Machine (JVM) is an engine that provides a runtime environment to drive the Java Code or applications. It converts Java bytecode into machine language. JVM is a part of the Java Run Environment (JRE). In other programming languages, the compiler produces machine code for a particular system. However, the Java compiler produces code for a Virtual Machine known as Java Virtual Machine.

Why JVM?

Here are the some important reasons of using JVM:

JVM provides a platform-independent way of executing Java source code.

It has numerous libraries, tools, and frameworks.

Once you run a Java program, you can run on any platform and save lots of time.

JVM comes with JIT (Just-in-Time) compiler that converts Java source code into low-level machine language. Hence, it runs faster than a regular application.

JDK

JDK is a software development environment used for making applets and Java applications. The full form of JDK is Java Development Kit. Java developers can use it on Windows, macOS, Solaris, and Linux. JDK helps them to code and run Java programs. It is possible to install more than one JDK version on the same computer.

Why use JDK?

Here are the some important reasons of using JDK:

JDK contains tools required to write Java programs and JRE to execute them.

Compiler converts code written in Java into byte code.

It includes a compiler, Java application launcher, Appletviewer, etc.

Java application launcher opens a JRE, loads the necessary class, and executes its main method.

JRE

JRE is a piece of software that is designed to run other software. It contains the class libraries, loader class, and JVM. In simple terms, if you want to run a Java program, you need JRE. If you are not a programmer, you don't need to install JDK, but just JRE to run Java programs.

Why use JRE?

Here are the some important reasons of using JRE:

JRE contains class libraries, JVM, and other supporting files. It does not include any tool for Java development like a debugger, compiler, etc.

If you have to run Java applets, then JRE must be installed in your system.

It uses important package classes like math, swing, util, lang, awt, and runtime libraries.