Optional Arguments Set default arguments, when we don't need to call it, we can simply skip it. def new_game(name, year=nil, system=nil) { name: name, year: year, system: system } end game = new_game("Street Figher II") Options Hash Argument Som…

HeadFIrst Ruby 第二章总结 methods and classes 前言 这一章讲了如何创建自己的 class,并且讲了在用 class 创建 object 的两个要素: instance variables 和 instance methods.和它们需要注意的一些问题. 创建 method 相关 问题1:括号 be or not be? 在 Ruby 中,如果需要创建的 method 包含参数,那么后面应该有“()” ;如果不需要任何参数,则不需要加“()”,在调用函数的时候也…

阅读了Java的官方Doc,在此总结如下. Abstract Class & Method In jave, "abstract" can be a modifier to class and method. Abstract class: A class that is declared abstract—it may or may not include abstract methods. Abstract classes cannot be instantiated, b…

define simple method定义简单方法 关键字def用于方法定义,在其后是方法名和可选的参数名列表,参数名列表会用一对圆括号括住.构成方法主体的代码放在参数列表之后,end用于结束方法定义. #define a method def factorial(n) if n<1 raise "argument must be >0" elsif n==1 1 else n*factorial(n-1) end end puts factorial(5) 方法返回值…

Information hiding is important for many reasons, most of which stem from the fact that it decouples the modules that comprise a system, allowing them to be developed, tested, optimized, used, understood, and modified in isolation. Advantage Speeds u…

5.1. Classes, Superclasses, and SubclassesLet's return to the Employee class that we discussed in the previous chapter. Suppose (alas) you work for a company at which managers are treated differently from other employees. Managers are, of course, jus…

ruby中顶层(top level)中定义的方法放在main中,证明如下: self.private_methods(false) #IN TOP LEVEL 那么methods方法究竟是在哪定义的,书上说是在Object中,但在ruby1.9.2p290中是在Kernel中定义的,证明如下: Kernel.public_instance_methods(false)…

java - @Override is not allowed when implementing interface method - Stack Overflow https://stackoverflow.com/questions/15402615/override-is-not-allowed-when-implementing-interface-method Intellij IDEA Module 的Language Level的问题 - LarryZeal - 博客园 http…

Reusing Classes 有两种常用方式实现类的重用,组件(在新类中创建存在类的对象)和继承. Composition syntax Every non-primitive object has a toString() method, and it’s called in special situations when the compiler wants a String but it has an object. Inheritance syntax You’re always do…

referee:Java Programming Tutorial Advanced Input & Output (I/O) JDK 1.4+ introduced the so-called New I/O int java.nio package and its auxiliary packages to support high performance and intensive I/O operations. NIO is meant to complement the existin…