I see many different Java terms floating around. I need to install the JDK 1.6. It was my understanding that Java 6 == Java 1.6. However, when I install Java SE 6, I get a JVM that reports as version 11.0! Who can solve the madness?
6 Answers
- JDK - Java Development Kit
- JRE - Java Runtime Environment
- Java SE - Java Standard Edition
SE defines a set of capabilities and functionalities; there are more complex editions (Enterprise Edition – EE) and simpler ones (Micro Edition – ME – for mobile environments).
The JDK includes the compiler and other tools needed to develop Java applications; JRE does not. So, to run a Java application someone else provides, you need JRE; to develop a Java application, you need JDK.
Edited: As Chris Marasti-Georg pointed out in a comment, you can find out lots of information at Sun's Java web site, and in particular from the Java SE section, (2nd option, Java SE Development Kit (JDK) 6 Update 10).
Edited 2011-04-06:
The world turns, and Java is now managed by Oracle, which bought Sun. Later this year, the sun.com domain is supposed to go dark. The new page (based on a redirect) is this Java page at the Oracle Tech Network. (See also java.com.)
Edited 2013-01-11: And the world keeps on turning (2012-12-21 notwithstanding), and lo and behold, JRE 6 is about to reach its end of support. Oracle says no more public updates to Java 6 after February 2013.
Within a given version of Java, this answer remains valid. JDK is the Java Development Kit, JRE is the Java Runtime Environment, Java SE is the standard edition, and so on. But the version 6 (1.6) is becoming antiquated.
Edited 2015-04-29: And with another couple of revolutions around the sun, the time has come for the end of support for Java SE 7, too. In April 2015, Oracle affirmed that it was no longer providing public updates to Java SE 7. The tentative end of public updates for Java SE 8 is March 2017, but that end date is subject to change (later, not earlier).
When you type "java -version", you see three version numbers - the java version (on mine, that's "1.6.0_07"), the Java SE Runtime Environment version ("build 1.6.0_07-b06"), and the HotSpot version (on mine, that's "build 10.0-b23, mixed mode"). I suspect the "11.0" you are seeing is the HotSpot version.
Update: HotSpot is (or used to be, now they seem to use it to mean the whole VM) the just-in-time compiler that is built in to the Java Virtual Machine. God only knows why Sun gives it a separate version number.
With the release of Java 5, the product version was made distinct from the developer version as described here
Version 1.5.0 or 5.0?
Both version numbers "1.5.0" and "5.0" are used to identify this release of the Java 2 Platform Standard Edition. Version "5.0" is the product version, while "1.5.0" is the developer version. The number "5.0" is used to better reflect the level of maturity, stability, scalability and security of the J2SE.
"Version 5.0" Used in Platform and Product Names
Version 5.0 is used in the platform and product names as given in this table:
| Full Name | Abbreviation | |
|---|---|---|
| Platform name | Java™ 2 Platform Standard Edition 5.0 | J2SE™ 5.0 |
| Products delivered under the platform | J2SE™ Development Kit 5.0 | JDK™ 5.0 |
| J2SE™ Runtime Environment 5.0 | JRE 5.0 |
"Version 1.5.0" Used by Developers
J2SE also keeps the version number 1.5.0 (or 1.5) in some places that are visible only to developers, or where the version number is parsed by programs. As mentioned, 1.5.0 refers to exactly the same platform and products numbered 5.0. Version numbers 1.5.0 and 1.5 are used at:
- java -version (among other info, returns java version "1.5.0")
- java -fullversion (returns java full version "1.5.0-b64")
- javac -source 1.5 (javac -source 5 also works)
- java.version system property
- java.vm.version system property
- @since 1.5 tag values
- jdk1.5.0 installation directory
- jre1.5.0 installation directory
- http://java.sun.com/j2se/1.5.0 website (http://java.sun.com/j2se/5.0 also works)
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