In
Java, lots of things are important to study but there are some basic terms every
java programmer should have knowledge about. These are the internal terms used
in Java programming language. I’m here giving you explanation about those terms
JRE, JDK and JVM.
JRE
(Java Runtime Environment)
JDK
(Java Development Kit)
JVM
(Java Virtual Machine)
JVM (Java Virtual Machine)
Java
virtual machine is a type of virtual environment in which java bytecode can be
executed. This virtual environment having architecture through which java
bytecode goes through before execution. Architecture of JVM has many phases.
When
we write a java command in command prompt for executing java class then after
writing this java command an instance of JVM is created.
JVM
is platform dependent, because different hardware and software has its
different JVM.
JVM
architecture has different phases:
It loads
bytecode in JVM, after this verifies that code then, execute given bytecode and
at last provide runtime environment.
JVM
works in a flow from entering the bytecode into it and till execution of that
bytecode.
Such as:
First
Classloader loads class of bytecode
into JVM,
Then,
JVM allocate memory to different things used in program like variables,
constants, functions etc.
At last,
an execute engine reads all bytecode
and execute all the instructions.
JRE (Java Runtime Environment)
Java
Runtime Environment is what who does work what actually JVM says. So JRE makes
a runtime environment using libraries and files. Or we can say it is the
implementation of JVM.
When
we install Java into our system a folder of jre is also there in java folder of
program files. So this jre folder contains those libraries and files which
creates a runtime environment for java programs.
JDK (Java Development Kit)
Java
Development Kit is the package we get from Java makers to develop applications
using java programming language. So JDK contains JRE and development tools to
develop java applications.
After
installing java we get a folder of java in program files, each and every things
this java folder contains comes under JDK.
So we
can say JDK is the universal set of JRE, JVM, and other development tools.
I
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