Here you can find the source of isSimpleType(Class clazz)
public static boolean isSimpleType(Class clazz)
//package com.java2s; //License from project: Open Source License import java.util.*; public class Main { private static final Set<Class> SIMPLE_TYPES = new HashSet<Class>( Arrays.asList(String.class, Date.class, Calendar.class, Boolean.class, Character.class, Byte.class, Short.class, Integer.class, Long.class, Float.class, Double.class, Void.class)); public static boolean isSimpleType(Class clazz) { return clazz.isPrimitive() || clazz.isEnum() || SIMPLE_TYPES.contains(clazz); }/*from w ww. j ava 2s . co m*/ }