programming in scala

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--"

Scala Language Basics 1. Scala morphology The character set used by the Scala program is the basic Multilingual plane character set for Unicode, and the following defines the two modes of Scala morphology: Scala mode and XML schema. If not specifically stated, the foll

The take in list is implemented with Listbuffer:version 2.10.xHowever, in the 2.11.x version, it is not:override def take (n:int): list[A] = if (IsEmpty | | n val h = new::(head, Nil)var t = hvar rest = tailvar i = 1while ({if (rest. isEmpty) return this; i i + = 1val NX = new::(rest. Head, Nil)t.tl = NXT = NXrest = rest. Tail}h}final Case class:: [B] (override Val head:b, private [Scala] var tl:list[b]) extends List[b]declared as VAR allows listbuffe

Final Case class:: [B] (private var hd:b, Private[scala] var tl:list[b]) extends List[b]TL is limited access through private to ensure the immutability of TL, so that in the building of the head element HD different and then the list of the same new list can be directly pointed to the TL, efficient.This ensures both functional programming and efficient creation of new objects.interested friends please pay attention to DT Big Data Dream Factory public

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

3, hands on the abstract class in ScalaThe definition of an abstract class requires the use of the abstract keyword: The above code defines and implements the abstract method, it is important to note that we put the direct running code in the trait subclass of the app, about the inside of the app helps us implement the Main method and manages the code written by the engineer;Here's a look at the use of uninitialized variables in an abstract class: 4, hands-on trait in ScalaTrait

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 ... 85th: The powerful expressive battle of the for expression in ScalaGoal:Comparison and contact of higher order functions (FLATMAP,MAP) and for loops (initial)Gains:The back of the For loop is actually called map, but it is more likely to be programmed with a for loop if the statement is concise and expressive two.MORE:Run the instance code over and try it out.----

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

High-order function filter Source analysisPackage Com.dt.scala.forexpressionCase class Person (name:string, Ismale:boolean, children:person*)Object For_expressive {def main (args:array[string]) {Val Lauren = person ("Lauren", false)Val Rocky = person ("Rocky", True)Val Vivian = person ("Vivian", False, Lauren, Rocky)Val persons = List (Lauren, Rocky, Vivian)Val result = Persons filter (person =!person.ismale) FlatMap (person =(Person.children map (child = (Person.name, child.name)))println (Resu

The Akka provides scalable, real-time transaction processing capabilities.The Akka is based on actor and provides location transparency.The 1GB heap can have 2.5 million actors.Horizontal expansion, vertical expansion, fault tolerance 3 ways to solve.The actor of the tree structure, each actor has state and behavior.DT Big Data Dream Factory public account: Dt_spark.DT Big Data Dream Factory's public number is Dt_spark, every day will have big data actual combat video release, please continue to

= { //similar to defining a static method initialization, using C to refer to a method var c=c () c.apply () c.test () }}3. Use apply to achieve a singleton mode, let's do a test. Reference the associated object C with C and C1, respectivelyPackage Smart.iotclass Applyclass { }class a{ def Test () =println ("function test") def apply () =println ( "Hello class A");} Object b{ def apply () =println ("Hello object B");} Similar to a factory method, use the C apply method

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

The code jumps inside the for loop are map, withfilter, etc.For is more direct than MAP,FILTER,FLATMAP, can be implemented with a for replacementPackage Com.dt.scala.forexpressionObject For_advanced {def main (args:array[string]) {}def Map[a, b] (list:list[a], f:a = b): list[b] =for (element def Flatmap[a, B] (list:list[a], f:a = List[b]): list[b] =for (x def Filter[a] (list:list[a], f:a = Boolean): list[a] =for (Elem }DT Big Data Dream Factory public account: Dt_spark.DT Big Data Dream Factory'