Knowledge Points: 1. Conditional expression if (x>0) 1 Else 0 Scala each expression has a type, if it is the same type, and if it is a mixed-type expression, the public superclass of any.if (x>0) 1 may not have output values, in Scala, each expression should have some value, introducing the Unit class, writing (). if (x>0) 1 is equivalent to if (x>0) 1 else () 2. Statement termination, if you write a long s
Scala List class Faq:how do I create a list in Scala?You can create a Scala List in several different ways, including these approaches:
Lisp style
Java style
Using the List class range method
Using the List class fill method
Using the List class tabulate method
In this Scala List tutorial,
Scala REPLRes1,res2, ... res5 and so on, respectively, indicate the output result. If the result of a computed output is identified as Res2, then the res2 can be used directly in subsequent calls.Cases:Scala Worksheek in the Scala IDEThis is a very useful feature provided by the Scala IDE. Its function is the equivalent of Sc
1. Scala LearningOfficial website;Http://www.scala-lang.org/Http://www.scala-lang.org/download/A scalable language is a multi-paradigm programming language, similar to java, designed to integrate various features of object-oriented programming and functional programming.Scala runs on JVM.Scala has several key features that demonstrate its object-oriented nature. For example, each value in Scala is an object
Once an object is created, it will no longer change its contents, so that the object is immutable. This can be done without worrying about competition management when accessing objects in multiple threads, and Java's string is an example of an immutable object. Based on this, when you use Scala to create multithreaded applications, you can write unlocked code with the invariant state (immutable states) to write concise multithreaded code without worry
This chapter describes Scala's support for XML, including the main contents of this article at the level of headings.
A description of the concept and XML format of semi-structured data is skipped, directly into Scala's XML-related syntax and usage. First, XML syntax
The Scala command line can be entered directly at the beginning of a tag, and the compiler automatically enters the XML input pattern until it encounters a closing flag that matches the t
the system is windows. The installation configuration Scala is as follows:
One, install Scala
1,java6 above (recommended Java 7 +) installation
Address: http://www.oracle.com/technetwork/java/javase/downloads/index.html
Configuring environment variables after installation
2,scala 2.12.2
Address: http://www.scala-lang.org/download/
3. Download the post-installat
==>Introduction to the Scala language --The Scala programming language captures many developers ' eyeballs. If you skim through Scala's website, you'll think Scala is a purely object-oriented programming language that seamlessly combines imperative programming with functional programming styles and not too long ago, programming languages could be categorized as
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
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
Previous Article: Scala Tutorial: interaction with Java, everything is an object
This document is translated from the official Scala tutorial. to prevent misunderstanding, keep the original document for reference.
Due to space limitations, there are three articles.
Blog formats are not easy to adjust, interested friends can download PDF version: http://download.csdn.net/source/1742639
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6Condition class a
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
(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
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