64 bit applications

[Dhinesh babu]

Hi All,

If i develop an application in Java, How can i know whether it is 64 bit or for 32 bit OS ?

Thanks in advance,
Dhinesh

[Jesper de Jong]

You normally don't need to know. Java applications are independent of the "bitness" of the operating system. You don't need to do anything to make your application to run on a 32-bit or 64-bit operating system.

If you really want to know, you can look at the "os.arch" system property:

System.out.println("Operating system architecture: " + System.getProperty("os.arch"));

On the system which I'm using right now, which has 32-bit Windows Vista, it says "x86". I guess that for a 64-bit Windows system it would say "x86-64" or something similar.

[Ove Lindström]

Sun has a Java System property to determine the bitness of the JVM: 32 or 64:

sun.arch.data.model=32 // 32 bit JVM
sun.arch.data.model=64 // 64 bit JVM

You can use

System.getProperty("sun.arch.data.model")

to determine if its 32/64 from the program.

From the sun.docs:

When writing Java code, how do I distinguish between 32 and 64-bit operation?

There's no public API that allows you to distinguish between 32 and 64-bit operation. Think of 64-bit as just another platform in the write once, run anywhere tradition. However, if you'd like to write code which is platform specific (shame on you), the system property sun.arch.data.model has the value "32", "64", or "unknown".

[Jesper de Jong]

But note that sun.arch.data.model is a Sun-specific system property; it's not part of the official public Java API and it will most likely not exist on JVM implementations from different vendors.

[Ove Lindström]

Good point Jesper.

IBM use com.ibm.vm.bitmode.

So with all this info, it is possible to write a DetectJVM class. (or google it).

[Dhinesh babu]

Thanks folks,

I got it, and am really proud to be a part of Ranch.

[Campbell Ritchie]

Ove Lindström wrote: . . . So with all this info, it is possible to write a DetectJVM class. (or google it).

I recommend you Google it. It took me two minutes to write and execute. Life's too short waste two minutes.