BobMcGee BobMcGee - 3 months ago 9
Java Question

How can I tell if I'm running in 64-bit JVM or 32-bit JVM (from within a program)?

How can I tell if the JVM my application runs in is 32 bit or 64-bit? Specifically, what function or preference do I access to detect this within the program?

Answer

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 HotSpot FAQ:

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".

The only good reason is if your java code is dependent upon native libraries and your code needs to determine which version (32 or 64bit) to load on startup.

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