Here you can find the source of getConcurrentMap(int... size)
public static <K, V> ConcurrentHashMap<K, V> getConcurrentMap(int... size)
//package com.java2s; import java.util.concurrent.ConcurrentHashMap; public class Main { public static <K, V> ConcurrentHashMap<K, V> getConcurrentMap(int... size) { if (size.length == 0) { return new ConcurrentHashMap<K, V>(); } else {//from w w w .ja v a 2 s. c o m return new ConcurrentHashMap<K, V>(size[0]); } } }