Count the number of CPUs in your system

import java.io.*;

class Test {

       static private boolean isWindows = System.getProperty("os.name").startsWith("Windows");

       static private int n_CPUs = 0;

       static public int getCPUCount() {

              if (n_CPUs > 0) return n_CPUs;

              if (isWindows) return 1; // no clue

              // POSIX systems, attempt to count CPUs from /proc/stat

              try {

                     Runtime runtime = Runtime.getRuntime();

                     Process process = runtime.exec("cat /proc/stat");

                     InputStream is = process.getInputStream();

                     InputStreamReader isr = new InputStreamReader(is);

                     BufferedReader br = new BufferedReader(isr);

                     String line;

                     n_CPUs = 0;

                     // valid cores will print as cpu0, cpu1. cpu2 ...

                     while ((line = br.readLine()) != null) {

                            if (0 == line.indexOf("cpu") && line.length() > 3

                            && Character.isDigit(line.charAt(3))) {

                                   n_CPUs++;

                            }

                     }

                     // fix possible errors

                     if (0 == n_CPUs) n_CPUs = 1;

                     return n_CPUs;

              } catch (Exception e) {

                     //Utils.log(e.toString()); // just one line

                     return 1;

              }

       }

       public static void main(String args[]) {

              System.out.println("No of CPU = "+getCPUCount());

       }

}