Difference betwen JRE, JDK, and SDK ???

[Guest_imported]

Hi I am a Java newbie... ^_^
I just notice that Sun provides three types (or more) of java software, such as JRE, JDK, SDK ... I just want to know the difference between them. Which one that consists java.exe and javac.exe... is it the JDK ?

Thanx

 

[meadandale]

JRE = Java Runtime Environment
This is needed to run java on your machine. It is included in most of the java downloads.

JDK = Java Development Kit
The original name for the developers download which included the JRE plus the developers tools (e.g. javac.exe).

SDK = Standard Development Kit
When Sun started releasing multiple Development kits, e.g. J2EE and J2ME, it renamed the standard JDK as SDK to differentiate it from the other tools.

 

[LeonTang]

just to add on abit more... JDK and SDK both contains JRE. JRE is required to run java applications. So if you are not a java developer but wants to run java applications that are compiled(class files) all you need is to download JRE.

J2EE is for building enterprise applications. Consist of servlets, jsp, enterprise java beans, etc.

J2ME is about the same as SDK except that it contains lesser packages. J2ME is used for developing Java applications that you want to use on devices like handphones. E.g. There is this new phone(I forgot the model) that allows you to upload your own Java application into the phone. If I am not wrong, the phone itself should contain J2ME in order to run your java app.

Hope this helps,
Leon If you need additional help, you can email to me at zaoliang@hotmail.com I don't guaranty that I will be able to solve your problems but I will try my best

 

[ikalair]

Hi. I'm a newbie as well.

Just so i have it all right:

SDK originates from JDK. To create and compile Java programs, i can use either one - since both come with the necessary tools (javac,java,etc.). If this is the case, which one do i actually use?

I've been using JDK 1.1.8 so far for basic programming such as loops,if statements,etc(to get familiar with Java syntax). I'm now reading about packages and in the book i'm reading (Beginning Java2 JDK 1.3 Edition), it says to put the packages in jre/lib/ext directory. Since the title of the book has JDK 1.3, i went ahead and downloaded JDK from java.sun.com. But the directory structure mentioned in the book isn't in JDK but its in SDK!

Rather confused here. Could someone help clear up this matter. I'm trying to learn the language, but i'm stuck here spinning my wheels in the basic fundamentals.

Should i be using JDK or SDK 1.4? They both have the necessary tools to develop Java programs. Are both necessary? Does one complement the other?

Help!!!!!!!!!

 

[segmentationfault]

javac is the compiler. Simple usage would be "javac HelloWorld.java"

java is the RTE. Simple usage would be "java HelloWorld"

You do not need both the SDK and JDK. My advice to you would be to keep the one that most closely resembles your book.