scala in depth

Now, here are the steps to build your development environment:Because Scala is a language on the JVM, we first install the Java Runtime environment. Download and install JDK8 from Oracle official website. Note that Scala only needs to run the Java environment, that is, to install only: JRE, but in order to facilitate future Java development, we still install the Java development environment. After the insta

There are several zip-related functions in Scala, such as zip,zipall,zipped, Zipwithindex, and so on. We often see such functions in our code, and this article mainly introduces the differences and uses of these functions.1, the ZIP function will pass in two parameters in the corresponding position of the elements to form a pair array. If one of the parameter elements is longer, then the extra parameters are deleted. Look at the English introduction:R

(Bus). Only through horizontal expansion (scale out), that is, distribution expansion by increasing the computer server and then using the distributed computing technology to divide the computational task into discrete servers for processing; This is the core of big data technology.Predictably, we will face the future: distributed data, high concurrency processing, parallel computing, NoSQL and very large interactive complex network platform programming. As a veteran programmer, experienced fro

Scala list/sequence faq:how do I iterate over a Scala List (or more generally, a sequence) using the foreach method or for loop?There is a number of ways to iterate over a Scala List using the foreach method (which was available to Scala sequences like ,,,, List Array ArrayBuffer Vector Seq , etc.) for and comprehensio

1. JDK official website address: https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html Scala is based on Java and uses a large number of Java class libraries and variables. Therefore, you must install Java before using Scala. Install JDK and select the installation path Check whether the installation is successful Open CMD and enter Java-version. If the Java version is

1. Download Scala 2.9.2 Since the latest Scala 2.10 stabilizer is not finished, it's best to download the latest Scala stable version: 2.9.2.Download Address: Http://www.scala-lang.org/downloads/distrib/files/scala-2.9.2.msiThe advantage of downloading the MSI version is that the environment variable is automatically

First, download Scala installation package From the official Scala website address: http://www.scala-lang.org/download/Download Scala binary package, in 2.11.8 version For example two, installation 1. Move the downloaded binary package to the/usr/local directory and unzip the package Tar zxvf scala-2.11.8.tgz MV

Tags: in addition to the input situation Eclipse blog free org Speed waterBuild maven Scala projects with eclipse1. Install the Scala IDE first, help-->eclipse Marketplace---> Enter scala--and install.2, select the following 4 need to install3, then install down, until the installation is complete.Second, in addition to installing the

01. Introduction and installation of Scala 1.1 Scala introductionScala is the Java language scripting, the feature is that the Java language is not scripted to use the script, so that it has a simple script language, WYSIWYG features, and high programming efficiency, fast implementation and other characteristics. In the big Data world, the famous frameworks for Spark and Kafka are written in the

Functional Object Advantages and disadvantages of immutable object Adv 1. Immutable objects are more likely to be inferred because they do not change values over time. Adv 2. immutable objects can be automatically transmitted without changes. To transfer a mutable object, you must first back up the mutable object to prevent modification to the object state in other processes. Adv 3. The thread cannot change the state of an immutable object (corruption, corruption). It is destined to be thread-sa

1.scala InterpreterThe installation process is similar to a JDK installation, you need to install the JDK first, and then download and install Scala to configure the PATH environment variable.2. Run cmd in the win environment using WIN+R, bring up the command window, execute the callout command①scala Support TAB Command Auto-completion②

As we all know, Scala is a functional programming language of the Geek type, and the features supported include: The function has a "class citizen" status; Support for anonymous functions (volume of function numbers) Supports higher order functions Support closures Partial application functions Currying The first point to note is that there are two forms of methods and function objects in

(transformation) and the Action (action). The main difference between the two types of functions is that transformation accepts the RDD and returns the RDD, while the action accepts the RDD to return the non-rdd.The transformation operation is deferred, meaning that a conversion operation that generates another RDD from an RDD is not performed immediately, and the operation is actually triggered when there is an action action.The action operator triggers spark to submit job jobs and outputs the

Avoid null useMost languages have a special keyword or object that represents an object that refers to a "none", in Java, which is null. In Java, null is a keyword, not an object, so it is illegal to call any method on it. But this is a confusing choice for language designers. Why do you want to return a keyword when the programmer wants to return an object?The option type of ScalaIn order for everything to be more consistent with the object's goal, and to follow the habit of functional programm

Reprinted from Fineqtbull http://fineqtbull.iteye.com/blog/477994One of the JE Students came to me and asked me about the Scala type parameter covariance, inversion, type upper bound and type of the lower bound of the use of methods and principles, although I have just learned, in the main investigation of the "programing in Scala" Chapter 19, try to do a summary below. If there are errors, please correct t

This article describes how to implement the basic Scala language types.Java basic type Java data types can be roughly divided into two types: Basic (Primitive) Type and object type. There are eight basic types: Boolean, byte, short, Char, Int, long, float, and double. To integrate the basic types into the OO system, Java provides (Wrapper). Package class in packageJava. LangThere are a total of 8 corresponding to the basic types: Boolean, byte, short,

Built-in control structures built-in control structure 1 if control structure Scala's if structure is the same as that of Java, and the function is not much different. Scala's saying is that if can return a value Val filename = If (! Args. isempty) ARGs (0) else "default.txt" This statement is relatively common, but a VaR is not introduced here, but the Val is used. Println (filename) is equivalent to println (if (! Args. isempty) ARGs (0) else "default.txt"), which is also an advantage of Val,

Note: The Scala version I used is 2.11.8 First, the Hello World code, as follows: Object helloscala{ def main (args:array[string]): Unit = { println ("Hello World ...")} } Here is a brief description of some of Scala's knowledge Points: first, Scala data types Scala's data types include: Byte, Char, short, Int, Long, Float, Double, Boolean Note: Scala