scala book

methods for traversing collections 1. Iterating through a collection with a foreach Loop foreach receives a function as a parameter. The defined function should receive an element as an input parameter, and then do not return anything. The type of the input parameter should match the type in the collection. With the execution of foreach, it passes an element to your function every time, until the last element in the collection. The most common use of foreach is output information:

The concepts of classes and methods in Scala are similar, and here are just some of the important concepts of Scala: 1.Public is the default access level for Scala and can be omitted. An important feature of the method parameters in 2.Scala is that they are all Val, not Var (the argument is Val is easier to articulate,

Guide to Statistics network This paper introduces Scala's language characteristics from seven aspects, such as installation, basic data type, operator, function and so on. Not just a Python programmer, anyone with programming experience or a desire to get started can look at it and make a basic understanding of Scala. With the needs of business and data, we have introduced spark. Spark's support for Python is fine, but it has been developed using

To create a string: The most straightforward way to create a string is to write a method that: var greeting = "Hello world!"; Or var greeting:string = "Hello world!"; Whenever you encounter a string in code, the compiler creates a string object and its value in this example using: "Hello world!", but if you like, you can give the string, because here I have alternately shown in the declaration. Object Test { Val greeting:string = "Hello, world!" def main (args:array[string]) { printl

This article is mainly about Scala concurrent (parallel) programming, then why the topic is called Geotrellis use (vi), mainly because this series explains how to use Geotrellis, the specific previous several blog has been introduced. I think the basis of doing any one thing is very important, like the college entrance examination or a variety of examinations, teachers will emphasize the basis, which is very reasonable. The basics of using the Geotrel

First lesson: Getting Started with ScalaThe great value of 1:scala2:scala basic function Getting started combat3:scala function Getting Started combatArray,map,tuple Combat in 4:scala5: Comprehensive case and spark source code analysisThe relationship between Scala and Java:One: They're all JVM-based, but Scala can inv

A systematic study of Scala has recently begun. In fact, I used Scala before, for example, when I was using Gatling's performance testing tool, I was exposed to Scala. Gatling itself is written in Scala, and the Gatling performance Test profile itself is a Scala class that i

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

ArrayLike an array of Java, it is also an immutable arrays, and since both Scala and Java are running in the JVM, both sides can call each other, so the bottom of the Scala array is actually a Java array. Note: Accessing an array of elements using () instead of [] in Java Scala>ValA =NewArray[string] (Ten) a:array[string] = Array (NULL,NULL,NULL,NUL

The first step is to build the Scala development environment and find tutorials on the web.declaring constants and variablesval foo = 0 //constant var bar = 0 //variable　　In Scala, it is more encouraged to declare using Val, which is the recommended constant. Most of the time do not need a semicolon, look at their own good ... Although it is a strongly static type of language, it does not write the type-t

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

"Editor's note" Although Java has won a lot of developers love, but compared to other modern programming languages, its syntax is indeed slightly lengthy. But with Java8, you can write code that is both readable and concise by using lambda expressions directly. The author Hussachai Puripunpinyo's software engineer, who analyzed the differences in performance and expression by comparing Java 8 and Scala, and discussed in depth the differences between t

)), (1+ (0+1)) + (0+1) + (1+ (0+1))) = Go (1,3,5)7 Go (0,5,8) = 5Is the answer we expected.The function of Scala is worth mentioning. A function can be used as a standard object: it can be treated as an input parameter or a result value of another function. Functions that accept a function as an input parameter or return another function as a result are called higher order functions (high order function). The use of anonymous functions (anonymou

, Int] = { if0) Left("Dude, can‘t divide by 0") else Right(x / y)}divideBy2(10match { case Left(s) => println("Answer: " + s) case Right(i) => println("Answer: " + i)}//print "Answer: Dude, can‘t divide by 0"In addition to using the Match case method to get the data, we can also use the. Right.get and. Left.get methods separately, and of course you need to use. isright or. Isleft to judge first. The left or right types also have filter, FlatMap, foreach, GET, Getorelse, map methods, and they

Hey, the company recently needs to test spark performance and catch up.After that Lua, Scala is also a simple look,,,In fact, I bought a 129-dollar spark book in March, the only one in the country.Package Com.hengheng.scalaclass Helloscala {}object Helloscala { def hello (name:string): String = { "Hello" + N Ame } def helloscala () { println ("Hello Scala