How to detect android device is 64 bit or 32 bit processor?

Simple answer: There’s no need to check for this on Android versions below Lollipop. That’s due the fact that Lollipop introducted platform support for 64-Bit architectures, Android-Versions below Lollipop won’t run with a 64-Bit processor.

Android 5.0 introduces platform support for 64-bit architectures—used
by the Nexus 9’s NVIDIA Tegra K1. Optimizations provide larger address
space and improved performance for certain compute workloads. Apps
written in the Java language run as 64-bit apps automatically—no
modifications are needed. If your app uses native code, we’ve extended
the NDK to support new ABIs for ARM v8, and x86-64, and MIPS-64.
(Source)

 try {
            boolean  isArm64 = false;

            BufferedReader localBufferedReader = new BufferedReader(new FileReader("/proc/cpuinfo"));
            if (localBufferedReader.readLine().contains("aarch64")) {
                isArm64 = true;
            }
            localBufferedReader.close();
        } catch (IOException e) {
        }

Or

final boolean is64bit = Build.SUPPORTED_64_BIT_ABIS.length > 0;

Firdt connect the device ato system,
on windows type in the command prompt this command

adb shell cat  /proc/cpuinfo | findstr arc

on linux or mac base system open terminal and type this command

  adb shell cat  /proc/cpuinfo | grep arc

if first line of out contain 32 that mean system type is 32bit

first line of out if contain 64 that mean system type is 64bit

32Bit if below 5.0, because android support 64Bit Until 5.0.
Judge whether Build.SUPPORTED_ABIS support 64 if above 5.0.

String bits;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    bits = TextUtils.join(", ", Build.SUPPORTED_ABIS).contains("64") ? "64-Bit" : "32-Bit";
} else {
    bits = "32-Bit";
}

You can view a device is 64bit or 32bit by using Dev Tools.

If you’re using ADB

adb shell cat /proc/cpuinfo | grep rch

Most outputs:

Architecture 7 -> 32bit

Architecture 8 -> 64bit

• this is an extension answer from @Naval Kishor Jha

• tested in 6 models here

• no root needed

I found the API, distinguish by app process.

Process.is64Bit()

Of course, it can be arm 64 or x86-64.

But if you only package arm share library, the x86 device can’t install you app.

So the method is work.

If you package x86 share library, then above answer SUPPORTED_ABIS is work.