scala in action

Java programmers, why do you need to pay attention to Scala, Java programmers, and Scala? Let's take a look at Martin Odersky's design goals for Scala. What aspects should be taken into account in the process of creating a language that surpasses Java? Concession Frank Sommers: You mentioned earlier that you want to create a language that exists in the Java

The main contents of this section Introduction to Scala I/O operations Scala Writing Files Scala Read files Scala Network I/O Introduction to Regular expressions Scala regular-expression combat 1. Introduction to

Let's look at a loop in Java: for (int i = 1; i ) { + ",");}There is no doubt that Scala can make this loop more concise. According to the previous section, it is not necessary to display the type of the specified variable i, and we do not even need to declare the variable. The next output statement can be more concise, and in Scala you can use the println () method to output a string directly. Finall

Package Com.leegh.parameterizationImport Com.leegh.parameterization.Compound_Type/*** @author Guohui Li*/Trait Compound_type1;Trait Compound_type2;Class Compound_type extends Compound_type1 with compound_type2Object Compound_type {def compound_type (x:compound_type1 with compound_type2) = {println ("Compound Type in Global Method")}def main (args:array[string]): Unit = {Compound_type (new compound_type1 with Compound_type2)Object Compound_type_object extends Compound_type1 with compound_type2Com

Package Com.leegh.parameterization/*** @author Guohui Li*/Class Pair_ordering[t:ordering] (Val first:t, Val second:t) {def bigger (implicit ordered:ordering[t]) = {if (Ordered.compare (first, second) > 0) First Else second}}Object Context_bounds {def main (args:array[string]): Unit = {Val pair = new pair_ordering ("Spark", "Hadoop")println (Pair.bigger)Val pairint = new Pair_ordering (3, 5)println (Pairint.bigger)}}Report:This blog description:1. Organize your ideas and improve yourself.2. Be ed

We do spark development using a lot of spark's higher-order functions so today I'm using scala higher-order functions on Linux ServicesDeclares a list collection:The package containing the list is already automatically introduced by the predefined, so there is no need to introduce a package here, directly using the list instantiation object, actually using the list object object's Apply methodWe use the map function to multiply each value in the list

Package Com.leegh.implicits/*** @author Guohui Li*/Object Context_implicits {Implicit val default:string = "Java"}Object Param {def print (content:string) (implicit language:string) {println (language + ":" + content)}}Object Context_parameters {def main (args:array[string]): Unit = {Param.print ("Spark") ("Scala")Import Context_implicits._Param.print ("Hadoop")}}Report:This blog description:1. Organize your ideas and improve yourself.2. Be educated i

We know that everything in Scala is an object, a function is an object, a number is an object, and it's a more object-oriented language than Java.Simple classes that define ScalaClass Point(val x:int, val y:int) The previous line of code is the definition of a Scala class: The first is the keyword class followed by the class name point The parentheses after the class name are the const

Package Com.leegh.parameterization/*** @author Guohui Li*/Because breathe returns This,scala the return type is inferred as animal, and because animal has no eat methodClass Animal {def breathe = this}Class Cat extends Animal {def eat = this}Class Animal {def Breathe:this.type = this}Class Cat extends Animal {def eat:this.type = this}Object Singleton_types {def main (args:array[string]): Unit = {Val cat = new CatCat.breathe.eat}}Report:This blog descr

Note: This study originates from: DT Big Data DreamWorks (public number: Dt_spark)1. Download the Scala installation package First:For subsequent spark Learning, we need to choose version:2.10.4Http://www.scala-lang.org/download/2.10.4.html2. After installation, choose the Scala IDE, one is the Eclipse Scala IDE, the other is Intellij ideaBecause of personal pref

Note: This study originates from: DT Big Data DreamWorks (public number: Dt_spark)1. Download the Scala installation package First:For subsequent spark Learning, we need to choose version:2.10.4Http://www.scala-lang.org/download/2.10.4.html2. After installation, choose the Scala IDE, one is the Eclipse Scala IDE, the other is Intellij ideaBecause of personal pref

Scala getting started-10 implicit conversions, implicit parameters, implicit classes, scala-10 So far, implicit conversion is the key and difficulty of scala ~ First, create a class named Implicit. scala. Let's look at an example of an implicit parameter: The implicit parameters are used in the above exampl

Scala: Pack, scala Scala has the same purpose as a java package or a c ++ namespace. It can contribute content to multiple packages in the same file. Use the full package name whenever possible. Avoid using scala, java, com, org, and so on to name nested packages. The concatenation package statement can limit the v

A, Scala is a compiled language, you can call Java code at will;B, Scala Functional programming language, in the Scala world, the function is a class citizen; Functions can be passed as parameters, can be assigned to variables, and can be returned as return values in Scala, there are nested functions, anonymou

First, the foregoing The functions in Scala are still more important, so this article enumerates the functions that may be used in Scala and explains them in detail. Second, the specific function 1, the definition of Scala function def fun (A:int, b:int): unit = { println (a+b) } Fun (1,1) def fun1 (a:int, b:int) = A+b printl N (fun1 (1,2)) No

Package Com.leegh.parameterization/*** @author Guohui Li*/Import Scala.reflect.ClassTagClass Trible[f, S, T] (Val first:f, Val second:s, Val third:t)Object Hello_type_parameterization {def main (args:array[string]): Unit = {val triple = new Triple ("Spark", 3, 3.1415)Val bigdata = new triple[string, String, Char] ("Spark", "Hadoop", ' R ')def Getdata[t] (list:list[t]) = List (LIST.LENGTH/2)println (GetData (List ("Spark", "Hadoop", ' R '))Val F = getdata[int]_println (f (List (1,2,3,4,5,6,7,8)))

Github:https://github.com/nscala-time/nscala-timeMAVEN: (Pay attention to the Scala version)Dependency> groupId>Com.github.nscala-timegroupId> Artifactid>nscala-time_2.10Artifactid> version>2.6.0version>Dependency>code example:Remember import com.github.nscala_time.time.imports._ scala> DateTime.Parse ("20150101", DateTimeFormat forpattern ("YyyyMMdd"))Res11:org.joda.time.DateTime = 2015-01-01t00:0

Scala Learning six: special characters in Scala special characters in Scala instructions for use: Object Scalaoperator {def main (args:array[string]) {///::: Three colons: 2 collections merged println ("-------[:::]") Val list1 = List (1, 2) Val list2 = List (3, 4) Val listcombine = List1::: List2 Listcombin E.foreach (x = {println (x)}) println ("-----

public number is Dt_spark, every day will have big data actual combat video release, please continue to study.Liaoliang DT Big Data dream factory Scala all videos, PPT and code in Baidu Cloud disk link:http://pan.baidu.com/share/home?uk=4013289088#category/type=0 Qq-pf-to=pcqq.groupLiaoliang "Scala Beginner's introductory classic video course" http://edu.51cto.com/lesson/id-66538.htmlLiaoliang "

Package Com.leegh.actorImport Scala.actors.Actor/*** @author Guohui Li*/Object First_actor extends Actor {Def Act () {for (I println ("Step:" + i)println (Thread.CurrentThread (). GetName)Thread.Sleep (2000)}}}Object Second_actor extends Actor {Def Act () {for (I println ("Step further:" + i)println (Thread.CurrentThread (). GetName)Thread.Sleep (2000)}}}Object Hello_actor {def main (args:array[string]): Unit = {First_actor.start ()Second_actor.start ()}}Report:This blog description:1. Organize