instanceof

封装 定义 隐藏内部细节，提供公共的访问方法，便于调用。提高程序可展性、维护性。实现高内聚，低耦合 语法 私有化属性，提供公共的 get/set 方法 体现 属性、方法、构造器、内部类 class 的权限修饰只可以用 public 和 default( 缺省 ) 。 核心是访问权限 访问权限 本类 同包 子类 其他 private √ 缺省 √ √ protected √ √ √ public √ √ √ √ 好处 提高程序可展性、维护性。实现高内聚，低耦合 继承 定义 继承 多个类有相同的属性和方法时，将这些相同的属性和方法提取到一个类中，让多个类和这个类产生的一种关系 子类、超类、基类 此处的多个类称为子类，单独的这个类称为父类（基类或超类）。可以理解为 : “子类 is a 父类” 语法 class Subclass extends Superclass{ // 代码 } 好处 1 、 继承的出现提高了代码的复用性。 2 、 继承的出现让类与类之间产生了关系，提供了多态的前提。 3 、 不要仅为了获取其他类中某个功能而去继承 , 要考虑类之间是否有分类学关联 子类可以继承父类的内容 所有成员，不包括构造器 继承特性 1 、 子类继承了父类，就继承了父类的方法和属性。 2 、 在子类中，自动拥有父类中定义的方法和属性，也可以创建新的数据和方法。 3 、 在 Java 中

1.RequestMappingHandlerMapping 1.继承了InitializingBean 加载所有的 Controller.class 和 RequestMapping.class 2. WebMvcAutoConfiguration 初始化时加载interception 3.根据url 获取在RequestMappingHandlerMapping获取handlerMethod，并包装成HandlerExecutionChain，并将RequestMappingHandlerMapping中的intercepters加入到 HandlerExecutionChain 加入规则如下 protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) { HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ? (HandlerExecutionChain) handler : new HandlerExecutionChain(handler)); String lookupPath = this.urlPathHelper

instanceof can be used to test if an object is a direct or descended instance of a given class. instanceof can also be used with interfaces even though interfaces can't be instantiated like classes. Can anyone explain how instanceof works? First of all, we can store instances of classes that implements a particular interface in an interface reference variable like this. package com.test; public class Test implements Testeable { public static void main(String[] args) { Testeable testeable = new Test(); // OR Test test = new Test(); if (testeable instanceof Testeable) System.out.println(

I'm designing a game. In the game, various game objects extend different interfaces (and one abstract class) depending on what they need to be doing, and are passed to handlers which take care of items with a specific interface at defined intervals (they actually spread all their work out in a neat sort of way to make sure input/video/etc is always processed). Anyway, some of these objects extend the abstract class Collider and are passed to a CollisionHandler. The Collider class and handler take care of everything technical involved in collision, and just ask that an object implement a

Dart specification states: Reified type information reflects the types of objects at runtime and may always be queried by dynamic typechecking constructs (the analogs of instanceOf, casts, typecase etc. in other languages). Sounds great, but there is no instanceof -like operator. So how do we perform runtime type-checking in Dart? Is it possible at all? Patrick The instanceof-operator is called is in Dart. The spec isn't exactly friendly to a casual reader, so the best description right now seems to be http://www.dartlang.org/articles/optional-types/ . Here's an example: class Foo { } main() {

Is there any way to efficiently check if the variable is Object or Array, in NodeJS & V8? I'm writing a Model for MongoDB and NodeJS, and to traverse the object tree I need to know if the object is simple (Number, String, ...) or composite (Hash, Array). It seems that V8 has fast built-in Array.isArray , but how to check if object is an Object? I mean complex object like hash {} or instance of class, not something like new String() ? Usually it may be done as this: Object.prototype.toString.call(object) == "[object Object]" or this: object === Object(object) But it seems that this operations

引言 Spring中提供了各种Aware接口，方便从上下文中获取当前的运行环境，比较常见的几个子接口有：BeanFactoryAware,BeanNameAware,ApplicationContextAware,EnvironmentAware，BeanClassLoaderAware等，这些Aware的作用都可以从命名得知 Aware 处理 其中 BeanNameAware 、 BeanClassLoaderAware 和 BeanFactoryAware 这三个是直接在bean的初始化之前就处理了的，具体代码在 AbstractAutowireCapableBeanFactory.initializeBean 方法中： protected Object initializeBean(String beanName, Object bean, RootBeanDefinition mbd) { // 判断对象实现的接口类型，处理特定的三种接口类型：BeanNameAware、BeanClassLoaderAware和BeanFactoryAware。 if (bean instanceof BeanNameAware) { ((BeanNameAware) bean).setBeanName(beanName); } if (bean instanceof

前言 JS作为面向对象的弱类型语言，继承也是其非常强大的特性之一。那么如何在JS中实现继承呢？让我们拭目以待。 既然要实现继承，那么首先我们得有一个父类，代码如下： // 定义一个动物类 function Animal (name) { // 属性 this.name = name || 'Animal'; // 实例方法 this.sleep = function(){ console.log(this.name + '正在睡觉！'); } } // 原型方法 Animal.prototype.eat = function(food) { console.log(this.name + '正在吃：' + food); }; 1、原型链继承 核心： 将父类的实例作为子类的原型 function Cat(){ } Cat.prototype = new Animal(); Cat.prototype.name = 'cat'; //　Test Code var cat = new Cat(); console.log(cat.name); console.log(cat.eat('fish')); console.log(cat.sleep()); console.log(cat instanceof Animal); //true console.log(cat