What is the difference between JDK and JRE?

Question

What is the difference between JDK and JRE?

What are their roles and when should I use one or the other?

Answer 1

From Official java website...

JRE (Java Runtime environment):

• It is an implementation of the Java Virtual Machine* which actually executes Java programs.
• Java Runtime Environment is a plug-in needed for running java programs.
• The JRE is smaller than the JDK so it needs less Disk space.
• The JRE can be downloaded/supported freely from https://www.java.com
• It includes the JVM , Core libraries and other additional components to run applications and applets written in Java.

JDK (Java Development Kit)

• It is a bundle of software that you can use to develop Java based applications.
• Java Development Kit is needed for developing java applications.
• The JDK needs more Disk space as it contains the JRE along with various development tools.
• The JDK can be downloaded/supported freely from https://www.oracle.com/technetwork/java/javase/downloads/
• It includes the JRE, set of API classes, Java compiler, Webstart and additional files needed to write Java applets and applications.