Here you can find the source of getWrapperTypeByPrimitive(Class> clazz)
public static Class<?> getWrapperTypeByPrimitive(Class<?> clazz)
//package com.java2s; //License from project: Apache License import java.util.*; public class Main { private static final Map<Class<?>, Class<?>> primitiveWrapperTypeMap = new HashMap<Class<?>, Class<?>>(8); public static Class<?> getWrapperTypeByPrimitive(Class<?> clazz) { return primitiveWrapperTypeMap.get(clazz); }//from www . j a v a2 s. c om }