Running 32-bit dll on 64-bit machine in java

Question

I am attempting to use a 3rd-party dll for a program I am writing in java. Unfortunately, it only has 32-bit support. When I attempt to load the dll in a 64-bit VM, I get the following error:

Can't load IA 32-bit .dll on a AMD 64-bit platform

I have tried running in a 32-bit VM, which works in eclipse, but when I export the project, I get the same error. Please help!

Sincerely, Ben

Answer 1

You cannot use a 32-bit DLL in a 64-bit Hotspot JVM. It won't work. And I don't know of any other 64-bit JVM that supports 32-bit DLLs.

Indeed, as Peter Lawrey points out, this is not just a JVM limitation. No mainstream operating system allows an application running in 64-bit mode to load and use a 32-bit library.

Your choices are:

• Switch to a 32-bit JVM. (You can run a 32bit JVM on a 64-bit OS ...)
• Port the DLL to 64-bit.
• Switch to an alternative library that is pure Java, or has a 64-bit DLL.

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I have tried running in a 32-bit VM, which works in eclipse, but when I export the project, I get the same error.

That can only mean that you are running a 32-bit JVM to run the application within Eclipse, and a 64-bit JVM to run the application outside of Eclipse. (The issue is how you run the application, not how you export it ...)

Answer 2

The only way to use a 32-bit shared library from a 64-bit JVM is to run an additional 32-bit JVM and access it via RMI, JMS or some form of messaging.

Its an intrinsic limitation of 64-bit programs (not just Java) that it cannot exchange pointers with a 32-bit library.