Here you can find the source of hash(Object obj)
public static int hash(Object obj)
//package com.java2s; //License from project: Open Source License public class Main { public static int hash(Object obj) { final int prime = 31; int result = 1; result = prime * result + ((obj == null) ? 0 : obj.hashCode()); return result; }// ww w .j a va 2 s . c o m }