What is the difference between JVM, JDK & JRE

JVM

The Java Virtual machine (JVM) is the virtual machine that run the Java bytecodes. The JVM doesn't understand Java typo, that's why you compile your *.java files to obtain *.class files that contain the bytecodes understandable by the JVM. It's also the entity that allows Java to be a "portable language" (write once, run anywhere). Indeed there are specific implementations of the JVM for different systems (Windows, Linux, MacOS, ..), the aim is that with the same bytecodes they all give the same results.

JRE

Java Runtime Environment (JRE) The Java Runtime Environment (JRE) provides the libraries, the Java Virtual Machine, and other components to run applets and applications written in the Java programming language. In addition, two key deployment technologies are part of the JRE: Java Plug-in, which enables applets to run in popular browsers; and Java Web Start, which deploys standalone applications over a network. It is also the foundation for the technologies in the Java 2 Platform, Enterprise Edition (J2EE) for enterprise software development and deployment. The JRE does not contain tools and utilities such as compilers or debuggers for developing applets and applications.

JDK

Java Development Kit (JDK) The JDK is a superset of the JRE, and contains everything that is in the JRE, plus tools such as the compilers and debuggers necessary for developing applets and applications.

Simply:

JDK (Java Development Kit) :

contains tools needed to develop the Java programs.
You need JDK, if at all you want to write your own programs, and to compile them.

JRE (Java Runtime Environment) :

Java Runtime Environment contains JVM, class libraries, and other supporting files. JRE is targeted for execution of Java files.

JVM (Java Virtual Machine) :

The JVM interprets the byte code into the machine code depending upon the underlying operating system and hardware combination. It is responsible for all the things like garbage collection, array bounds checking, etc… Java Virtual Machine provides a platform-independent way of executing code.

Also Read :

1. Installing Java 7 on Ubuntu

2. Why we Pass String array as argument to main method in Java

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