edx scala

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.parameterization/*** @author Guohui Li*/Object Type_contraints {def main (args:array[string]): Unit = {def Rocky[t] (i:t) (implicit ev:t println ("Life is too short,you need spark!")}Rocky ("Spark")}}Report:This blog description:1. Organize your ideas and improve yourself.2. Be educated in Liaoliang teacher, what to gain, so recommend.3. Blog focus on practice, superfluous words are not much to say, are doing technology.4. Information from DT Big Data Dream Factory public accou

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/6F/91/wKioL1WhEYHR0V55AAi8dfKDnAg782.jpg "title=" 002- Scala function definition, Process Control, exception handling get started in combat. png "alt=" wkiol1wheyhr0v55aai8dfkdnag782.jpg "/>002-scala function definition, Process Control, exception handling getting started combatScalafunction Definitionstatement end no semicolondefining an parameter

3, hands-on generics in Scalageneric generic classes and generic methods, that is, when we instantiate a class or invoke a method, you can specify its type, because Scala generics and Java generics are consistent and are not mentioned here. 4, hands on. Implicit conversions, implicit parameters, implicit classes in Scalaimplicit conversion is one of the key points that many people learn about Scala, which i

Scala code in one day (5) and scala code in one dayScala code in one day (5)To better control spark, I recently studied scala language features, mainly reading "quick learning scala" and writing down some codes that I think are useful. Package examplesclass Person {val publicVal = 1 // automatically generate getter var

Answer the previous article.1. Is there also a syntax for declaring upper bound and Lower Boud in Java? Some, such as:ListWhat is the difference between listListListPackage Tstge;import java.util.*;p ublic class Tst {public static void main (string[] args) {arraylistThe type of 3.Java can usually be translated directly into the Scala type. But like IteratorIterator[t] Forsome {type T} or Iterator[_]Iterator[t] Forsome {type T About Forsome,stack overf

1, Java Operation Test jar: Execute---java-classpath f:/testhello.jar Test2 Or JAVA-CP F:/testhello.jar Test2 Print Results: Hello World The Java classes are as follows: /** * Document: This kind of function----> Print Hello World * USER:YANGJF * date:2016/9/25 9:48 /Public Class Test2 {public static void Main (string[] args) { System.out.println (' Hello World '); } 2, Scala operation Test jar: Execute--"

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

Note: This study originates from: DT Big Data DreamWorks (public number: Dt_spark)In Scala , we usually use syntax similar to function calls. For example, if s is a string, then s (i) is the first character of the string . (And in java , you would write:s.charat (i).) Run the following code in idea:println ("Hello (4)")//will print out ' o 'You can use this as an overloaded form of the () operator, and the implementation behind it is a method called

001-scala Development environment Construction and HelloWorld parsing650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/6F/7A/wKiom1Wd1vGx30HBAAST-S83WFU734.jpg "title=" 001- Scala development Environment Building and HelloWorld parsing. png "alt=" wkiom1wd1vgx30hbaast-s83wfu734.jpg "/>scalafunctional programming and object-oriented languagefunctional Programming excels at numerical calculationsObj

Upper bound and lower bound Declare Lower bound with:>, which is the parent class constraint, a:> B, a must be the parent of BWith Examples of Lower boundPackage Ch6object Test4 {println ("Welcome to the Scala Worksheet") class A {type B;: List[int] def foo (A: B) = a} val x = new A {type b = Traversable[int]} Set (1) X.foo (set (1))//Val y = new A {type b = set[int ]}//Compilation Error}Thus, the meaning of a:> B is: The parent class of B or a t

1. Create a map 1) Create immutable mappings scala> val status = Map (1, "a", 2, "B") status:scala.collection.immutable.map[int,string] = map (1-A , 2-B) scala> val status = Map ((1, "a"), (2, "B")) status:scala.collection.immutable.map[int,string] = Map (1-A, 2-B) 2) Create a mutable mapping either by importing it into the scope or by specifying the full path to the Scala.collection.mutable.Map class w

NothingNothing is a subclass of all types, and is also a subclass of NULL. Nothing has objects, but can be used to define types. For example, if a method throws an exception, the return value type of the exception is nothing (although it is not returned).def get(index:Int):Int = { if0thrownew Exception(...) else ....}If the statement is an expression with a return value, there must be a return value type, if x NullNull is a subclass of all Anyref, in Scala's type system, Anyref is a subcla

it's so ....Come back at night suddenly saw into the huge manuscript, can't help to the three ye, and then nothing did 23 o'clock ... 88th: Scala uses the for expression to implement map, FLATMAP, filterGoal:For expression Implementation Map/flatmap/filterGains:Map/flatmap/filter is a generic typeMORE:。。。。。。------------------------------------------------------------------------------------information from DT Big Data Dream Factory public account:Dt_s

One of the core features of functional programming is to pass functions as parameters to functions, to define functions inside functions, and so on.1, hands-on Scala high-order functionsDeclares a list collection instance: The package that contains the list collection is already pre-defined and automatically imported, so there is no need to import the package here, and this is where the list instantiation object is used, which is actually the App

This is a Scala by Example from the official website.The example of how Scala is used in more detail after tutorial1.Programing with Actors and Message2.Expressions and Simple Functions3.first-class Functions4.Class and Objects5.Case Classes and Pattern Matching6.Generic Types and Methods7.Lists8.for-comprehensions9.Mutable State10.Computing with Streams11.Lazy Values12.Implicit Parameters and Conversions13

Basic content1. Array definitionsDefinition of fixed length, variable array, element addition, deletion, sorting, summation and other common operationsImport Scala.collection.mutable.ArrayBufferimport scala.math.bigdecimal.roundingmode/** * @author Xwolf * @date 2017-04-09 18:23 * @since 1.8 */object Collection {def main (arg:array[string]): Unit ={Multiplearray ()}/** * Array Creation */private def create (): unit={val a = new array[string] (1) A (0) = "Hello" println (A.tobuffer) Val A b =a

for (generator; definition; filter) to Do data filtering queryPackage Com.dt.scala.forexpressionCase Class Book (title:string, Authors:list[string])Object For_query {def main (args:array[string]) {Val Books:list[book] = List (Book ("Structure and Interpretation", List ("Abelson, Harold", "Sussman"),Book ("Principles of Compiler Design",List ("Aho, Alfred", "Ullman, Jeffrey")),Book ("Programming in Modula-2", List ("Wirth, Niklaus")),Book ("Introduction to Functional Programming", List ("Bird, Ri