32 bit machine or 64 bit machine

[Kapil Gupta]

Hi All,
Is there any way that java can find out whether it is running on 64bit architecture or 32 bit?

I have searched net and found two possible workarounds:

boolean is64bit;
String osArch = System.getProperty("os.arch").toLowerCase();
is64bit = osArch.indexOf("64") >= 0;

OR

String bits = System.getProperty("sun.arch.data.model", "?");
if (bits.equals("64")) {
is64bit = true;
}
else if (bits.equals("?")) {
// probably sun.arch.data.model isn't available
// maybe not a Sun JVM?
// try with the vm.name property
is64bit = System.getProperty("java.vm.name").toLowerCase().i ndexOf("64") >= 0;
}
// probably 32bit
else
is64bit = false;

but both of them not working in my case. (Vista 64 bit and XP 64 bit).
Depending on the architecture I have to browse some different folders.
Is there any robust method to find out the architecture of the machine?

Thanks in anticipation,
Kapil

[Eranga]

Did you try to get the model using sun.arch.data.model property? It gives the data model/data transfer model.

[Kapil Gupta]

Thanks Eranga for your reply.

I have already tried:
String bits = System.getProperty("sun.arch.data.model", "?");
if (bits.equals("64")) {
is64bit = true;
}
.....

but this explains the JVM type 64 bit or 32 bit.
Isn't there anyway to find out the processor type ( 64 or 32 ).

I thought of getting output of dos command systeminfo to get the processor type
System type: X86-based PC/x64-based PC

Is there any other workaround?

Thanks,
Kapil

[Eranga]

Really, I think it related to OS. Anyway I have one idea, that OS bit model and H/W bit model should be same right?

If so, we can find the OS bit model, and use it to processing.

[Kapil Gupta]

Eranga,
Can you help me with finding "OS bit model" using java?
How can I find this?

Thanks,
Kapil

[Eranga]

There should be a system property to find this. Can't we find such a one.

[Kapil Gupta]

Hi Eranga,

Actually I was testing the above two workarounds with a jar file. I was double clicking the jar and was not able to get the output for os.arch and sun.arch.....

But when I ran the jar from command prompt by using command

java -jar -cp . Filename.jar ,

both of these methods are showing proper results for 64 bit machine. Can somebody explain why is this so ?

Thanks,

Kapil

[Eranga]

Quite similar question going on your another thread. I'll discussed it there.

[fishtoprecords]

You could always exec to some shell/os command and parse it.

But I know of no way to tell if you are running on a 64 bit processor that happens to be running a 32 bit OS. And these days, it is safe to assume that most 64 bit AMD/Intel processors are running a 32 bit OS.

More importantly, isn't the point of Java to make hardware implementation details unimportant?

[Eranga]

Quote:

Originally Posted by fishtoprecords

More importantly, isn't the point of Java to make hardware implementation details unimportant?

This is interesting for me. Even me, never worried about such h/w implementations on working with Java. And also I never comes with such issues before.

[fishtoprecords]

Part of the reason that Java defines 'long' and Long separate from int and Integer is to make the language independent of the processor. A proper Java JVM will execute the code and get the right answer on a 8 bit, 32 bit or 64 bit machine.

A lot of embedded systems are 8 bit processors, or 16, so in general its not safe to assume that you have 32 or 64 bits.

Long ago, there were many more flavors, systems with 7 bit characters, or 10 six bit characters, per "word" of memory. Most folks don't remember that stuff, since all PCs used the IBM mainframe convention of 8 bits per byte, and byte-based memory.

With network protocols, you have to worry about big-endian and little-endian, but internal register size is rarely an issue these days.

I guess that if you really wanted to have an array of 5gb of data, you would care, since a 32 bit machine can only address 4gb.

[Eranga]

Ya I agreed with you pal. Well said it.

[Niveditha]

Hi folks,
This is interesting to find out something new other than core java as we do always.

Kapil try this out:
System.getProperties().list(System.out);
The above stmt prints u some info related to OS such as version architecture n all.

If that is what u dont want then use JNI(Java native Interface), i am nt sure about its API's.

If taht wouldnt work out, the last thing u can do is find out a command line that will give u this information and java always provides u the way to execute them..

Hope ur problem is solved.

[Eranga]

I already do it and for me, there is no such a related option we can use. I found the h/w architecture and try to involve with it.