scala and akka

= { //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

:: 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

An expression Scala> 1 + 1 res0:int = 2 value You can assign the result of an expression to a variable (val) by name. scala> val two = 1 + 1 two:int = 2 variable If you need to modify the binding of this name and result, you can choose to use Var. scala> var name = "Steve" name:java.lang.String = Steve scala> name

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

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

security, consistency. Type systems include: generic classes, covariance and contravariance, callouts, upper and lower bounds of type parameters, class and abstract types as Object members, composite types, referencing themselves when displaying specified types, views, polymorphic methods. Scalability: Concurrency: Use actor as the concurrency model, but it differs from thread, which is equivalent to the thread's entity. In Scala, multiple ac

Recently, when processing data, you need to join the raw data with Redis data, in the process of reading Redis, encountered some problems, by the way to make a note, hoping for other students also helpful. During the experiment, it was not stressful to read Redis one at a time when the amount of data was 100,000 levels, but when the amount of data reached tens, the problem arose, even with the mappartitions of Spark. Therefore, consider using Redis's pipeline (if you have a better approach, plea

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

　　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