Here you can find the source of valueOf(Object o)
public static String valueOf(Object o)
//package com.java2s; //License from project: Open Source License public class Main { /** This works the same as {@link String#valueOf(Object)}, except it returns an empty string instead of "null" if the input is null. */ public static String valueOf(Object o) { return o == null ? "" : String.valueOf(o); }/*from www. j a v a 2s .c o m*/ }