Introduction to JDK,
JRE, and JVM
developed program in java we have need to understand concepts of JDK, JRE and
JVM in java.
JDK-: JDK (Java Development Kit) is a
bundle of software component. JDK is an implementation of either of Java SE,
Java EE or Java ME. It includes the Java
Runtime Environment (JRE), an interpreter/loader (java), a compiler (javac), an
archiver (jar), a documentation generator (javadoc) and other tools needed in
JRE-: JRE (Java Runtime Environment)
contains JVM, class libraries, and other supporting files. It does not contain
any development tools such as compiler, debugger, etc. Actually JVM runs the
program, and it uses the class libraries, and other supporting files provided
in JRE. If you want to run any java program, you need to have JRE installed in
JVM-: In java when we compile our code then
output not in exe file but it is a class
file and class file consists of java byte codes which are understandable by JVM
(Java Virtual Machine). JVM interprets the byte code to machine code depending
upon the underlying operation system and hardware combination. The JVM is
called “virtual” because it provides a machine interface that does not depend
on the underlying operating system and machine hardware architecture. JVM is
platform dependent. It
is responsible for all the things like garbage collection, array bounds
What is JIT Compiler (Just- In Time Compiler)?
is a component of JRE (Java Runtime Environment). It improves the performance
of Java Application’s by compiling bytecode to native machine code at run time.
When a Java program is run JVM launched that interprets the byte code and
provides result. At run
time, the JVM loads the class files, determines the semantics of each
individual bytecode, and performs the appropriate computation.