programming in scala

Note: This study originates from: DT Big Data DreamWorks (public number: Dt_spark)1.in the previous section we learned about Scala Hello World, specifically defining a function as follows:650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M02/70/40/wKiom1W1CI_DmfpAAAGAJtFJ734715.jpg "title=" 1.png " alt= "Wkiom1w1ci_dmfpaaagajtfj734715.jpg"/>2.define a function without parameters, as follows:650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M

Some time ago Read the "Fast Learning Scala", feel that writing is not very good, so began to see this "programming Scala", the book's Code has been realized a bit, now put in the blog to share. Package BASE04 /** * Scala's class * Created by DD on 2016/5/18 0018. * /Object demo01 extends app{ class car (val year:int) { private var milesdriven:int = 0 def miles () = Miles Driven def D

This article first describes how to configure the Maven+scala development environment in Eclipse, and then describes how to implement the spark local run. Finally, the spark program written by Scala is successfully run. At first, my Eclipse+maven environment was well configured. System: Win7 Eclipse version: Luna release (4.4.0) MAVEN is installed from the Eclipsemarket, as shown in Figure 1. When the Ecli

:: Appends the object to the head of the list.The head part of an existing list[subclass X] is placed in another object A, which is a subclass Y, and if both a object and the original list object inherit from the same parent class, the list is displayed as the list[parent class].The parameters of the function are contravariant so that covariance cannot occur, so the nether is used to solve the problem. The object to which the:: Method returns is programmed as a list of upper bound object B.inter

Package Com.dt.scala.listObject Listbuffer_internals {def main (args:array[string]) {Val list = list (1,2,3,4,5,6,7,8,9)Increment (list)Increment_moreeffective (list)Increment_mosteffective (list)}def increment (List:list[int]): list[int] = list match {Case list () = List ()Case HEAD:: tail = head + 1:: Increment (tail)}def increment_moreeffective (List:list[int]): list[int] = {var result = List[int] ()for (element Result}def increment_mosteffective (List:list[int]): list[int] = {Import Scala.co

Default value:def saymyname (name:string = "Jack") {println (name)}Variable parameters:def summoreparameters (elem:int*) = { var sum = 0for (e Use of underscores:def add (a:int,b:int) = a+bdef add2 = Add (_:int,2)Recursive functions: Need to explicitly give the return type of the functiondef FAC (n:int): Int = if (n function currying:Write this argument independently, this is curryingdef mulitply (X:int) (y:int) = x*ydef m2 = mulitply (2) _;Curry is the parameter can be separated, some of the

From Scala wizard Chapter 1 functional objects With the basic Scala knowledge gained from the previous chapters, you are ready to explore how to design objects with more comprehensive features in Scala. This chapter focuses on defining functional objects, that is, classes of objects without any variable states. As an example of running, we will create several Cl

Scala basic syntax If you have a good understanding of the Java language, it will be easy to learn Scala. The most important difference between Scala and Java is that the line terminator is optional. Consider a Scala program that can be defined as a collection of objects that communicate by calling each other's methods

This course focuses onSpark, the hottest, most popular and promising technology in the big Data world today. In this course, from shallow to deep, based on a large number of case studies, in-depth analysis and explanation of Spark, and will contain completely from the enterprise real complex business needs to extract the actual case. The course will cover Scala programming, spark core programming, spark SQL and spark streaming, spark kernel and source

==>Introduction to the Scala language --The Scala programming language captures many developers ' eyeballs. If you skim through Scala's website, you'll think Scala is a purely object-oriented programming language that seamlessly combines imperative programming with functional programming styles and not too long ago, programming languages could be categorized as

Match use case class: Case classes is used for pattern matching and case expression to specify the class. These are standard classes with special modifications: case. The following is a simple pattern that uses case class matching examples: Object Test { def main (args:array[string]) { Val alice = new Person ("Alice", 25) Val bob = new Person ("Bob", 32) Val charlie = new Person ("Charlie", 32) for (Person Person Match { Case person ("Alice") => println ("Hi alice!") Case person ("Bob

A concise course in Scala Directory Variable declaration Function Package Package Data String Control process Pattern matching Object-oriented Generic type Annotations Implicit Empty Object Nil,null,null,unit,nothing,none Scala is a multiple-paradigm (MULTI-PARADIGM) programming language. Scala source code is compiled into Java bytecode, so it can run on top

Class and constructors:The class is defined as follows: Class MyClass (A:int, b:int) { println (a.tostring) } In Scala, classes can also have class parameters, class parameters can be used directly in the body of the class, there is no need to define a field and then assign the constructor parameters to the field, but it should be noted that: the class parameter is just a parameter, not a field, if you need to use elsewhere, you must define the f

　　The first step: learning to use the Scala interpreterThe easiest way to start Scala is to use the Scala interpreter, which is an interactive "shell" that writes Scala expressions and programs. Scala needs to be installed before using S