RuntimeMemoryUsag

public class RuntimeMemoryUsageDemo {  
    public static void main(String[] args) {
        Runtime rt = Runtime.getRuntime();
        float max = rt.maxMemory() / 1024 / 1024; //convert bytes into MB
        System.out.println("Total "+max + " MB");
        long start = rt.freeMemory();
        StringBuffer sb = new StringBuffer("Hello");
        for (int i = 1; i <= 5000; i++) {
            sb.append("Testing");
        }
        long end = rt.freeMemory();
        float used = (start - end);
        System.out.println("Used memory: " + used + " Bytes");   
        rt.gc();//request  to garbage collector
        //System.gc();
    }
}