Java tutorial
//package com.java2s; import java.util.*; public class Main { public static int sizeOf(Collection collection) { if (isEmpty(collection)) { return 0; } return collection.size(); } public static boolean isEmpty(Map map) { return !isNotEmpty(map); } public static boolean isEmpty(Collection<?> collection) { return !isNotEmpty(collection); } public static boolean isNotEmpty(Map map) { return map != null && map.size() > 0; } public static boolean isNotEmpty(Collection<?> collection) { return collection != null && collection.size() > 0; } }