JAVA environment

JAVA environments include following things.

JDK
JRE
JVM

JDK(Java Development Kit) : Its purpose is to provide development environments for software developers.
It includes development tools such as the Java compiler, Jar, Javadoc, and a debugger.

JRE(Java Runtime Environment) : It contains the parts of the Java libraries which are required to run Java programs. It is for the purpose of end users.

Java Runtime Environment (JRE) can be view as a subset of Java Development Kit (JDK).

JVM (Java Virtual Machine): It is an abstract machine. JVM provides run time environments in which java bytecode can be executed. Many hardware and software platforms are supported by JVMs.