How to get the number of cores of an android device

Question

I was looking to determine(or count) the number of cores in the embedded processor of android device.

I tried using /proc/cpuinfo, but it is not return

Answer 1

good thing is to use JNI, if possible in project

std::thread::hardware_concurrency()

Answer 2

Here you go (JAVA) :

    try {
        int ch, processorCount = 0;
        Process process = Runtime.getRuntime().exec("cat /proc/cpuinfo");
        StringBuilder sb = new StringBuilder();
        while ((ch = process.getInputStream().read()) != -1)
            sb.append((char) ch);
        Pattern p = Pattern.compile("processor");
        Matcher m = p.matcher(sb.toString());
        while (processorCount.find())
            processorCount++;
        System.out.println(processorCount);
    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 3

You can try this method to get number of core.

 private int getNumOfCores()
      {
        try
        {
          int i = new File("/sys/devices/system/cpu/").listFiles(new FileFilter()
          {
            public boolean accept(File params)
            {
              return Pattern.matches("cpu[0-9]", params.getName());
            }
          }).length;
          return i;
        }
        catch (Exception e)
        {
              e.printstacktrace();
        }
        return 1;
      }

Answer 4

Use this to get no. of cores.Do read this link very carefully and also see what the author is trying to tell between virtual device and a real device.

The code is referred from THIS SITE

/**
 * Gets the number of cores available in this device, across all processors.
 * Requires: Ability to peruse the filesystem at "/sys/devices/system/cpu"
 * @return The number of cores, or 1 if failed to get result
 */
private int getNumCores() {
    //Private Class to display only CPU devices in the directory listing
    class CpuFilter implements FileFilter {
        @Override
        public boolean accept(File pathname) {
            //Check if filename is "cpu", followed by a single digit number
            if(Pattern.matches("cpu[0-9]+", pathname.getName())) {
                return true;
            }
            return false;
        }      
    }

    try {
        //Get directory containing CPU info
        File dir = new File("/sys/devices/system/cpu/");
        //Filter to only list the devices we care about
        File[] files = dir.listFiles(new CpuFilter());
        Log.d(TAG, "CPU Count: "+files.length);
        //Return the number of cores (virtual CPU devices)
        return files.length;
    } catch(Exception e) {
        //Print exception
        Log.d(TAG, "CPU Count: Failed.");
        e.printStackTrace();
        //Default to return 1 core
        return 1;
    }
}

Answer 5

Try this:

Runtime.getRuntime().availableProcessors();

This returns the number of CPU's available for THIS specific virtual machine, as I experienced. That may not be what you want, still, for a few purposes this is very handy. You can test this really easily: Kill all apps, run the above code. Open 10 very intensive apps, and then run the test again. Sure, this will only work on a multi cpu device, I guess.

Answer 6

Nice and simple solution in kotlin:

fun getCPUCoreNum(): Int {
  val pattern = Pattern.compile("cpu[0-9]+")
  return Math.max(
    File("/sys/devices/system/cpu/")
      .walk()
      .maxDepth(1)
      .count { pattern.matcher(it.name).matches() },
    Runtime.getRuntime().availableProcessors()
  )
}