1. The three principles of OOP are encapsulation(封装性), inheritance(继承性) and polymorphism(多态性). example: class Shape{ def area: Double = 0.0 } # supertype # subtypes class Rectangle(val width: Double, val height: Double) extends Shape{ override def ar…

1. Functional programming treats computation as the evaluation of mathematical and avoids state and mutable data. Scala encourages an expression-oriented programming(EOP) 1) In expression-oriented programming every statement is an expression. A state…

1. Scala is a contraction of "scalable" and "language". It's a fusion of objected-oritended and functional programming. 2. Compare Book class between Java and Scala Java: class Book{ private String title; private int numberOfPages; pub…

1. Translating Java Classes to Scala Classes Example 1: # a class declaration in Java public class Book{} # Scala equivalent of a class declaration class Book Example 2: # a Java class with a Construtor public class Book{ private final int isbn; priv…

1. Variables (1) Three ways to define variables: 1) val refers to define an immutable variable; scala> val x = x: Int = scala> x*x res4: Int = scala> res4 + # use result as a value res6: Int = scala> res4 + res6 res7: Int = scala> x = # x i…

1. Unified Type System Scala has a unified type system, enclosed by the type Any at the top of the hierarchy and the type Nothing at the bottom of the hierarchy. All Scala types inherit from Any. # Using Any, Book extends AnyRef, and x is an Int that…

Scala's object-oriented collections support mutable and immutable type hierarchies. Also support functional higher-order operations such as map, filter, and reduce that let you use expression-oriented programming in collections. Higher-order operatio…

The basic functional cornerstones of Scala: immutable data types, passing of functions as parameters and pattern matching. 1. Basic Pattern Matching In Scala, your cases can include types, wildcards, sequences, regular expressions, and so forth. scal…

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")} |…

Three characteristic of object orientation: Encapsulation: capturing data and keeping it safely and security from outside interfaces 使用private关键之修饰成员变量,成员方法,被修饰的只能在本类中被使用 public class Student{ private String name; private int age; // 每个成员变量对应的有一对sett…