Difference between JDK, JRE and JVM.

Hello viewers, Once again welcome back to Java Jagran. Today I am going to discuss "Difference between JDK, JRE and JVM". So Let's start:

JDK

• JDK is an acronym for Java Development Kit. 
• It physically exists. 
• It contains JRE + development tools. 

JDK is also known as Java Development Kit which provides all necessary tools to develop any Java application as well as run it.

JRE

• JRE is an acronym for Java Runtime Environment. 
• It is used to provide a runtime environment. 
• It is the implementation of JVM. 
• It physically exists. 
• It contains set of libraries + other files that JVM uses at runtime. 
• Implementation of JVMs is also actively released by other companies besides Oracle.

Java Runtime Environment provides all necessary libraries and files which is required by JVM to execute any bytecode/.class file. For example: If you want to run any applet on your browser you have to install JRE on your system.

JVM

• JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides a runtime environment in which java bytecode can be executed.
• JVMs are available for many hardware and software platforms. JVM, JRE and JDK are platform dependent because the configuration of each OS differs. But, Java is platform independent.
• The JVM performs following main tasks:

• Loads code
• Verifies code
• Executes code
• Provides runtime environment

As a developer, we write a Java program i.e *.java file. Further, we compile the Java program and the *.class file is generated which is also known as bytecode. Now to execute this bytecode we need a something. But what exactly is that? Java Virtual Machine(JVM) is a virtual machine which runs the Java bytecode/.class file and generates the output.