Here you can find the source of contains(Object o, Collection> c)
public static boolean contains(Object o, Collection<?> c)
//package com.java2s; //License from project: Apache License import java.util.Collection; public class Main { public static boolean contains(Object o, Collection<?> c) { if (c == null) { return false; }/*from www. j a v a 2 s .c o m*/ return c.contains(o); } }