Using scala is just another road, and it just like we fall in love again, but there is some pain you will have to get, and sure we deserve that to achieve the goal we want. In Scala, there is kind of constructors named auxiliary contructor, which hav…

Providing Constructors for Your Classes (The Java™ Tutorials > Learning the Java Language > Classes and Objects) https://docs.oracle.com/javase/tutorial/java/javaOO/constructors.html A class contains constructors that are invoked to create objects f…

/* * Copyright (C) 2016 Stephen Ostermiller * http://ostermiller.org/contact.pl?regarding=Java+Utilities * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by *…

档 ID 420787.1 White Paper Oracle Applications Multiple Organizations Access Control for Custom Code Checked for relevance on 12-JAN-2011 See Change Record This document discusses how to update the customization code that is affected by the access con…

关于反射 Reflection 面试题,什么是反射(反射的概念)? 主要是指程序可以访问,检测和修改它本身状态或行为的一种能力,并能根据自身行为的状态和结果,调整或修改应用所描述行为的状态和相关的语义. 反射机制就是在[运行]状态中,对于任意一个[类],都能够[知道]这个类的所有属性和方法:对于任意一个[对象],都能够[调用]这个对象的所有属性和方法:这种[动态获取类中的信息]以及[动态调用对象的成员]的功能称为java语言的反射机制. 但是它也有它的缺点,就是运用它会使我们的软件的性能降低,复…

4.实现多个接口Implementing Multiple Interface 接口的优势:马克-to-win:类可以实现多个接口.与之相反,类只能继承一个超类(抽象类或其他类). A class can implement multiple interface, but a class can have only one superclass. this is also the difference between abstract class and interface.例1.4:--- i…

问题 这个错误出现在case class参数超出22个的时候. case classes cannot have more than 22 parameters 在scala 2.11.x版本以下时case class 的参数最多为22个,如果超过这个参数又不能升级时(比如目前spark依赖于2.10.x)要怎么办? 解决方案 这里举个26个参数的例子,其余情况依此类推 class ABC ( a : String, b : String, c : String, d : Long, e : L…

A trait provides code reusability in Scala by encapsulating method and state and then offing possibility of mixing them into classes thus allowing code reuse. #define Trait Gliding scala> trait Gliding{ | def gliding(){ println("gliding")} |…

// the parent constructor function Parent(name) { this.name = name || 'Adam'; } // adding functionality to the prototype Parent.prototype.say = function () { return this.name; }; // empty child constructor function Child(name) {} inherit(Child, Paren…

官网教程 https://www.dartlang.org/guides/language/language-tour dart是一个单线程的语言,没有多线程 Final and const If you never intend to change a variable, use final or const, either instead of var or in addition to a type. A final variable can be set only once; a con…