Here you can find the source of max(Collection extends T> coll)
public static <T extends Object & Comparable<? super T>> T max(Collection<? extends T> coll)
//package com.java2s; /******************************************************************************* * Copyright (c) 2005, 2014 springside.github.io * * Licensed under the Apache License, Version 2.0 (the "License"); *******************************************************************************/ import java.util.*; public class Main { public static <T extends Object & Comparable<? super T>> T max(Collection<? extends T> coll) { return Collections.max(coll); }/*from w w w . j ava 2 s .co m*/ public static <T> T max(Collection<? extends T> coll, Comparator<? super T> comp) { return Collections.max(coll, comp); } }