Here you can find the source of isEmpty(Collection c)
public static boolean isEmpty(Collection c)
//package com.java2s; import java.util.Collection; public class Main { /** Check whether string s is empty. */ public static boolean isEmpty(String s) { return ((s == null) || (s.length() == 0)); }//from www.j a v a2 s. com /** Check whether collection c is empty. */ public static boolean isEmpty(Collection c) { return ((c == null) || (c.size() == 0)); } }