How to get JVM heap size, used memory, total memory using Java Runtime

Java’s Runtime class provide lot of information about the resource details of Java Virtual Machine or JVM. The memory consumed by the JVM can be read by different methods in Runtime class.
Following is the small example of getting/reading JVM Heap Size, Total Memory and used memory using Java Runtime api.

public class Memoryusage{

 

    public static void main(String [] args) {

 

        int mb = 1024*1024;

 

        //Getting the runtime reference from system

        Runtime runtime = Runtime.getRuntime();

 

        System.out.println("Heap Space usage in MB");

 

        //Print used memory

        System.out.println("Used Memory:"

            + (runtime.totalMemory() - runtime.freeMemory()) / mb);

 

        //Print free memory

        System.out.println("Free Memory:"

            + runtime.freeMemory() / mb);

 

        //Print total available memory

        System.out.println("Total Memory:" + runtime.totalMemory() / mb);

 

        //Print Maximum available memory

        System.out.println("Max Memory:" + runtime.maxMemory() / mb);

    }