How to get RAM size using java?

package com.demo.memoryheap;

import java.lang.management.ManagementFactory;

/**
 * @author abdul
 *
 */
public class FreeMemoryUsingMxBean {

    /**
     * @param args
     */
    public static void main(String[] args) {
        com.sun.management.OperatingSystemMXBean mxbean = (com.sun.management.OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
       
        System.out.println("Total Memory in MB: " + mxbean.getTotalPhysicalMemorySize()/(1024*1024));
       
        System.out.println("Free Memory in MB: " + mxbean.getFreePhysicalMemorySize()/(1024*1024));
    }
}

Note : If you get access restriction error while working on Eclipse , check this :
Access Restriction issue