Java and Eclipse - 32 vs. 64bit

Question

I'm a little bit confused about the two different versions of Eclipse - 32/64bit.

As far as I know, Java bytecode (= build of your code) is platform independend. If a user runs your bytecode in a 32bit JRE, the code is executed in as a 32bit process, if a user runs your bytecode in a 64bit JRE, the code is exectued as a 64bit process.

Eclipse needs the JRE to run, cause it's written in Java. But why are there 32 and 64bit versions of Eclipse on the Eclipse download page if only the user's JRE version does matter?

Does a 64bit Eclipse version need a 64bit JRE or JDK? If yes ,why?

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Second confusion: I understand the need for a 32 and 64 bit version of the JRE. But why are there 32 and 64 bit versions of the JDK if the resulting bytecode is platform independet?

Thank you

Answer 1

Eclipse relies on SWT, which is essentially native code. There will be quite a few DLLs etc. exists (in the plugins or features directories) that will be used by the 64-bit version, that are drastically different from the 32-bit version.

Answer 2

It is not because of the running environment, it is because Eclipse uses some native stuff and must be run on corresponding JDK. The applications you are developing inside Eclipse can then be run on whatever JRE you have installed, just specify it in the settings.

JDK is a compiler and also a lot of other stuff. Many of them are native applications that need to be run corresponding platform.