import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;

public class Main {
    private static OperatingSystemMXBean osMXBean;
    public static void main(String[] args) {
        osMXBean = ManagementFactory.getOperatingSystemMXBean();
        long ramSize = ((com.sun.management.OperatingSystemMXBean) osMXBean).getTotalPhysicalMemorySize();
        System.out.println("ramSize = " + ramSize);
    }
}