programming in scala

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

Label: Introduced Scala is a kind of functional object-oriented language . It blends a lot of unprecedented features. At the same time, it executes on top of the JVM . With the growing interest of developers in Scala , and the increasing number of tools to support it, the Scala language will undoubtedly be an indispensable tool in your hands. MongoDB is a product

(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,

Map Construction Map Immutable: Val map = map ("sa"-> 1, "S"-> 2)Map ("sa") = 3 // Error Val emptymap = new scala. collection. Immutable. hashmap [String, int] Variable: Val MAP2 = scala. collection. mutable. Map ("sa"-> 2)MAP2 ("sa") = 3 Val emptymap = new scala. collection. mutable. hashmap [String, int] Note:-> used to create tuples, "sa"-> 1 ("sa", 1) Initial

Install Scala 2.10.x in Ubuntu The default scala version on Ubuntu 14.04.1 LTS is 2.9, while the latest spark-1.3 requires the lowest version of scala 2.10.x, first, use apt-get remove scala to clear old scala versions on the machine. Download the http://www.scala-lang.org/

Mainly from the Coursera course "functional programming Principles in Scala"by Professor Martin Odersky, the inventor of the Scala language. 3. Data and Abstraction3.1 Class hierarchiesThis set of subtitles is out -,- of sync, listening to a little effort!The concept of a class is similar to that of other languages, such as base class, subclass, and parent class. In

Scala list faq:how do I add elements to a scala list?This was actually a trick question, because you can ' t add elements to a scalalist; It's an immutable data structure, like a Java String .prepending elements to Scala ListsOne thing you can does when working with a Scala was to List create a new from an List existin

Scala 学习One: Environment configurationScale official website address: http://scala-ide.org/download/sdk.html1: Install Java JDK2: Install Scala3: Install the Scala integrated IDESecond: Start the Scala learning journeyHello Scala Demo1: Create a new

We know that the IDE has a number of selected versions for development. As most of us often use is as follows.Eclipse * VersionEclipse * DownloadAnd we know that for the Scala development of Spark, there's a specially designed eclipse for it,Scala IDE for Eclipse　　1. Scala IDE for eclipse downloadhttp://scala-ide.org/

(Environment: Jdk1.7,scala plug-in scala-2.1.1.2-site.zip)1: Download Scala pluginHttp://download.scala-ide.org/sdk/helium/e38/scala211/stable/site 2: Unzip to LocalCopy all of the jar packages from the two files to the folder in the installation directory for Eclipse three: Restart Eclipse this will prompt you to have the plugin not enabled, click OK Four: Creat

Pattern matching using extractor: When an instance of a class is followed by parentheses using a list of 0 or more parameters, the compiler invokes the applied method on that instance. We can define both objects and classes. As mentioned above, the purpose of the Unapply method is to extract a particular value from what we are looking for. It operates in the opposite way as apply. An extract object that compares the Unapply method in a matching statement is automatically executed, as follows: Ob

Overview In short, implicit conversions are: When a Scala compiler does a type match, if the appropriate candidate is not found, implicit conversion provides another way to tell the compiler how to convert the current type to the expected type. The source of this article: http://blog.csdn.net/bluishglc/article/details/50866314 is strictly prohibited in any form of reprint, otherwise will entrust CSDN official maintenance rights and interests. Implici

how to rely on Scala's language features for high-force dependency injection What is dependency injection.Object is an abridged unit in the object-oriented world, and dependency injection groups the objects together. The simplest way to look at it is to inject the dependency into the object through a constructor or setter method.If we use the appropriate container, we can also extract the dependencies of each component of the system into the configuration file or configuration code, and inject

Implicit is a very important feature in Scala and has been thinking about it as much as Java before starting to learn Scala, but it's not as easy to see some of Scala's source code as it is, so I'm going to write a few articles to explain the features of Scala that are different from Java. Implicit, let's get started. In my opinion, what implicit do is also the m

Win7 installing Scala 2.111. Download Scala 2.11http://download.csdn.net/download/u014393736/7107595I really download the Scala installation files, in fact, is a compressed package, just need to extract the files can be!You can also download the MSI suffix file on the website to install it.The installation process is as follows:The advantage of downloading the MS

The main contents of this section Trait Construction Order Comparison of trait and classes Pre-defined and lazy loading Trait extension Classes Self type 1 Trait Construction OrderIn the previous note, we mentioned that for trait that do not have a specific implementation and a field, it will eventually generate a bytecode file that is equivalent to the interface in Java, whereas for trait with specific implementations and fields, the bytecode file is compiled with