JDK, JVM, JRE, JAVAC, JAR: Java

By Luis Mtz

Previous Post: Java Programming Language and Java Software Platform

If you red my previous post, you should already know what JVM, API and Java packages are, but, What are all of those Java words like JDK and JRE?  Java ME and Java SE?

Java Editions

• Java Card: A technology that allows small Java-based applications (applets) to be run securely on smart cards and similar small-memory devices.
• Java ME (Micro Edition): Specifies several different sets of libraries (known as profiles) for devices with limited storage, display, and power capacities. Often used to develop applications for mobile devices, PDAs, TV set-top boxes, and printers.
• Java SE (Standard Edition): For general-purpose use on desktop PCs, servers and similar devices.
• Java EE (Enterprise Edition): Java SE plus various APIs useful for multi-tier client–server enterprise applications.

JDK

JDK stands for Java Development Kit, and it’s a set of the tools that are needed for Java applications development. It includes the JVM and the JRE, as well as Java packages and framework classes, and the debugger (a computer program used to test and debug a program, often before compiling it, but not necessarily) and compiler. So, in order to develop a Java applications, you need the JDK.

JRE

If you are programming in Java, you are coding in .java files. These files are converted to bytecode files with .class extension, by a compiler named javac. If your program have a lot of classes, it can be distributed in a single .jar file that contains all of these .class files.

 A JVM is distributed along with Java Class Library, a set of standard class libraries (in Java bytecode) that implement the Java application programming interface (API). These libraries, bundled together with the JVM, form the Java Runtime Environment (JRE).

Next Post: Java Development Environment and the Hello World example

Sources:

http://en.wikipedia.org/wiki/JRE#Execution_environment

http://warleo.com/blog/?p=49

http://en.wikipedia.org/wiki/Debugger

http://en.wikipedia.org/wiki/Java_(software_platform)

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