How to test from java code if the jvm supports -d64 option?

Question

I thought about using the following code, but is there any cleaner way?

Process theProcess = Runtime.getRuntime().exec("java -d64 -version");
BufferedReader errStream = new BufferedReader(new InputStreamReader(theProcess.getErrorStream()));
System.out.println(errStream.readLine());

You should use `theProcess.waitFor() != 0` to decide whether it worked or not. Not *much* nicer though. — whiskeysierra, Aug 05 '10 at 19:25
@Thorbjorn: I need to startup some other java code with or without -d64 option, depending upon whether the jvm supports it or not. — rkatiyar, Aug 06 '10 at 08:08
Feels like a duplicate of [this](http://stackoverflow.com/questions/2062020/how-can-i-tell-if-im-running-in-64-bit-jvm-or-32-bit-jvm) — Gangadhar, Aug 06 '10 at 19:53

score 1 · Answer 1 · answered Aug 05 '10 at 14:11

1

If you are using Sun JVM, I think you can use the sun.arch.data.model system property (using the System.getproperty() to get this value.

answered Aug 05 '10 at 14:11

Gangadhar

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What if jvm is from a different vendor? – rkatiyar Aug 06 '10 at 06:20
I am not sure if the other JVMs have a property for this. – Gangadhar Aug 07 '10 at 18:01

score 1 · Answer 2 · answered Aug 05 '10 at 14:41

1

You can use

String arch = System.getProperty("os.arch")
if (arch.equals("amd64") || arch.equals("x86_64")) {
    // Machine is 64-bit
}

To determine whether the machine itself is a 64-bit machine. Not sure about checking the VM itself, though.

answered Aug 05 '10 at 14:41

Haldean Brown

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This is inaccurate and not to be trusted. – Jonathon Faust Aug 05 '10 at 19:34
and what if `arch.matches("[Aa]lpha.*")` which is a a 64-bit machine? and if "x86_128" supports the -d64 option you'd say it doesn't. – Stephen P Aug 05 '10 at 21:08

score 1 · Accepted Answer · answered Aug 05 '10 at 19:28

Decided to post this as an answer:

public static boolean supports64Bit() {
    try {
        final Process process = Runtime.getRuntime().exec("java -d64 -version");
        try {
            return process.waitFor() == 0;
        } finally {
            process.getInputStream().close();
            process.getOutputStream().close();
            process.getErrorStream().close();
        }
    } catch (IOException e) {
        // log error here?!
        return false;
    }
}

Closing all streams associated with a process is good practice and prevents resource leaks.

Not tested.

Another good idea is to do this only once and than cache the result in a static variable. — whiskeysierra, Aug 05 '10 at 19:30

score 0 · Answer 4 · answered Aug 06 '10 at 09:58

0

The simplest way to do so, may be through Java WebStart and a local JNLP file. You then invoke "javaws foo.jnlp" with appropriate options.

You can have architecture dependent options and libraries.

answered Aug 06 '10 at 09:58

Thorbjørn Ravn Andersen

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How to test from java code if the jvm supports -d64 option?

4 Answers4