Java tutorial
//package com.java2s; import java.util.*; public class Main { public static <T extends Object> boolean hasComplement(Collection<T> c1, Collection<T> c2) { if (c1 == null || c2 == null) return false; for (T t1 : c1) { if (!c2.contains(t1)) return true; } for (T t2 : c2) { if (!c1.contains(t2)) return true; } return false; } }