Here you can find the source of isSimpleType(Object obj)
public static boolean isSimpleType(Object obj)
//package com.java2s; //License from project: Open Source License import java.sql.Date; import java.sql.Time; import java.util.Locale; public class Main { public static boolean isSimpleType(Object obj) { if (obj == null) return true; return obj instanceof String || obj instanceof Integer || obj instanceof Long || obj instanceof Float || obj instanceof Double || obj instanceof Boolean || obj instanceof Locale || obj instanceof Date || obj instanceof Time; }// w w w. j a v a 2 s .c om }