udemy scala

Scala: Operator and parser, scala operator ParsingThe names of variables, functions, and classes are collectively referred to as identifiers. The backquotes can contain almost any character sequence.In scala,-Operator ending with Colon-Value assignment operatorAll operators are left-bound. The unapply method accepts an object and then takes the value from it, us

The trait definition in Scala includes a collection of fields, behaviors (methods/functions/actions), and some non-implemented functional interfaces that can be easily extended or mixed into existing classes or abstract classes.Scala's trait (trait) is a very useful feature that can be better abstracted in the design. The program is more extensible by making programs more focused on their features and better splitting the program into multiple trait m

Learn Scala together with Lian le-advanced type, scala-type Welcome to join Scala discussion QQ Group 212859367, and join! Singleton type Example: class Document{ def setTitile(title: String) = {...; this} def setAuthor(author: String) = {...; this} ...}val atticle.setTitle("whatever floats your boat").setAuthor("lianle") If the above classes have child

Scala learning notes, scala Learning The notes are complex! 1. The Singleton objects in Scala are decorated with objects, similar to static classes in C ++. When calling its internal functions, you can call them directly using the object name. You cannot apply for a new function! 2. A file can define classes and Singleton objects with the same name. A singleton O

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

In Java, variable types fall into two main categories: primitive types and reference types. Although the auto-boxing and auto-unpacking mechanisms have been introduced after JDK1.5, we have greatly reduced our entanglement between the direct and reference types, but there are still some issues that we have to consider. For example, I encountered a problem with the base type and the default value of its wrapper type, such as generics can only use reference types, such as by default the value of t

Scala Beginner's intermediate-Advanced Classic (66th: Scala concurrent programming experience and its application in Spark source code) content introduction and video link2015-07-24DT Big Data Dream FactoryFrom tomorrow onwards, be a diligent person.Watch videos, videos, share videosDT Big Data Dream Factory-scala--Advanced Classic: 66th: The first experience of

Scala is famous recently, but it is really so good. What I see is nothing. Scala's fame masks its shortcomings, so many people do not see its shortcomings. Although it is a functional programming language, it gives me the overall feeling of confusion and inconsistency, to be different, do you have to be different from other languages to show your excellence? You know, Java has been tested for more than 20 years. Isn't it worth learning from? Are you s

We talked about getting started with Scala, but after all, it's not like scripting language, and Scala is talking about replacing Java, so we'll see how he grabs the Java position.A common editor for Scala, see below: Eclipse (using one of the shoddy and unstable Scala plugins) Emacs IntelliJ (basicall

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

In this Martin and two other pattern matching experts ' papers, there are several ways to implement pattern matching, and Scala chooses which way to implement it.Http://lampwww.epfl.ch/~emir/written/MatchingObjectsWithPatterns-TR.pdfI quoted some of the descriptions inside.In object-oriented programs, data is organized into class-level classesThe problem with object-oriented language in pattern matching is how to detect this level from the outside.The

The main contents of this article are as follows: Variables and invariants Functions and procedures Parameters of the function Semicolon 1. Variables and invariants 1.1. VariablesScala's variables are divided into two types, Var and val. var, or variable, is similar to the variables we touch in other languages such as Java, and Val, is value, similar to the non-assignable constants we use in other languages, or the final variable.Why this difference, this is because in

Scala briefly -- class and object, scalaClass In scala, classes are not declared as public. The source file can contain multiple classes, all of which have common visibility. The getter and setter methods are provided for each field, which are called Field Names and field name_, respectively, and can be customized. Note: 1) if the field is private, getter and setter are also private. 2) if the field is val

Question: Convert the text string "[1, 2, 3, 4, 5]" to an array. Answer:val x = "[1, 2, 3, 4, 5]"Val y =x Slice (1, x.length-1) replace (",", "") Split ("")var y1= x Slice (1, x.length-1) replace (",", "") Split ("") Map (_.toint)Y1:array[int] = Array (1, 2, 3, 4, 5)or writevar y1= x.slice (1, x.length-1). Replace (",", ""). Split (""). Map (_.toint)OrVal y:array[int]= x Slice (1, x.length-1) replace (",", "") Split ("") Map (_.toint)Scala encourages

001-scala development environment Construction and HelloWorld parsingScala functional programming and object-oriented language functional programming excel at numerical computing object-oriented organization of large-scale engineering and project and team collaboration Scala will be the next great language? Spark is written in the Scala language, and Hadoop is wr

Scala: annotation and scala AnnotationAnnotations can be used to add information to various entries of a program. They are inserted into the code so that tools can process tags for them. You can use java annotations for scala classes or scala-specific annotations.In scala, a