Here you can find the source of getWrapper(Class clazz)
public static Class getWrapper(Class clazz)
//package com.java2s; //License from project: Apache License import java.util.Map; public class Main { private static Map<Class, Class> wrappers; public static Class getWrapper(Class clazz) { if (isPrimitive(clazz)) { return wrappers.get(clazz); }/*w ww . j a va 2 s . c o m*/ return clazz; } public static boolean isPrimitive(Class clazz) { return wrappers.containsKey(clazz); } }