Cfrgtkky

You can try on the command line:

java -d64 -version

If it's not a 64-bit version, you'll get a message that looks like:

This Java instance does not support a 64-bit JVM.
Please install the desired version.

Consult the help options of the JVM for more info java -help

Just type java -version in your console.

If a 64 bit version is running, you'll get a message like:

java version "1.6.0_18"

Java(TM) SE Runtime Environment (build 1.6.0_18-b07)

Java HotSpot(TM) 64-Bit Server VM (build 16.0-b13, mixed mode)

A 32 bit version will show something similar to:

java version "1.6.0_41"

Java(TM) SE Runtime Environment (build 1.6.0_41-b02)

Java HotSpot(TM) Client VM (build 20.14-b01, mixed mode, sharing)

Note Client instead of 64-Bit Server in the third line. The Client/Server part is irrelevant, it's the absence of the 64-Bit that matters.

If multiple Java versions are installed on your system, navigate to the /bin folder of the Java version you want to check, and type java -version there.

I installed 32-bit JVM and retried it again, looks like the following does tell you JVM bitness, not OS arch:

System.getProperty("os.arch");

#

# on a 64-bit Linux box:

# "x86" when using 32-bit JVM

# "amd64" when using 64-bit JVM

This was tested against both SUN and IBM JVM (32 and 64-bit). Clearly, the system property is not just the operating system arch.

Complementary info:

On a running process you may use (at least with some recent Sun JDK5/6 versions):

$ /opt/java1.5/bin/jinfo -sysprops 14680 | grep sun.arch.data.model

Attaching to process ID 14680, please wait...

Debugger attached successfully.

Server compiler detected.

JVM version is 1.5.0_16-b02

sun.arch.data.model = 32

where 14680 is PID of jvm running the application. "os.arch" works too.

Also other scenarios are supported:

jinfo [ option ] pid

jinfo [ option ] executable core

jinfo [ option ] [server-id@]remote-hostname-or-IP 

However consider also this note:

"NOTE - This utility is unsupported and may or may not be available in future versions of the JDK. In Windows Systems where dbgent.dll is not present, 'Debugging Tools for Windows' needs to be installed to have these tools working. Also the PATH environment variable should contain the location of jvm.dll used by the target process or the location from which the Crash Dump file was produced."

On Linux, you can get ELF header information by using either of the following two commands:

file {YOUR_JRE_LOCATION_HERE}/bin/java

o/p:
ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, not stripped

or

readelf -h {YOUR_JRE_LOCATION_HERE}/bin/java | grep 'Class'

o/p:
Class: ELF64

If you are using JNA, you can check whether com.sun.jna.Native.POINTER_SIZE == 4 (32 bit) or com.sun.jna.Native.POINTER_SIZE == 8 (64 bit).

Under Windows 7 in the "Control Panel" under "Programs | Programs and Features" the 64-bit variants of JRE & JDK are listed with "64-bit" in parentheses (e.g. "Java SE Development Kit 7 Update 65 (64-Bit)"), while for the 32-bit variants the variant is not mentioned in parentheses (e.g. just "Java SE Development Kit 8 Update 60").

For Windows, you can check the Java home location. If it contains (x86) it is 32-bit otherwise 64-bit:

public static boolean is32Bit()

{

    val javaHome = System.getProperty("java.home");

    return javaHome.contains("(x86)");

}



public static boolean is64Bit()

{

    return !is32Bit();

}

Example paths:

C:Program Files (x86)Javajdk1.8.0_181binjava.exe # 32-bit

C:Program FilesJavajdk-10.0.2binjava.exe # 64-bit

Why care about a Windows only solution?

If you need to know which bit version you're running on, you're likely fiddling around with native code on Windows so platform-independence is out of the window anyway.

If you're using JNA, you can do thisPlatform.is64Bit().

To get the version of JVM currently running the program

System.out.println(Runtime.class.getPackage().getImplementationVersion());