travis scala

Similar to Java,scala, there is also the concept of classes and objects. I. Classes, properties, and methods 1. ClassA class is an abstraction of a kind of thing, and when a class is defined, it can be defined as a template that defines a series of objects of that class. For example, you have one of the following templates Human: Having a name, having a brain, having limbs, having sex, being able to think, having a language ability; The a

IntroducedScala is a functional object- oriented language that incorporates many unprecedented features while running on top of the JVM . As developers become more interested in Scala , and more and more tools are available, the Scala language will undoubtedly be an essential tool in your hands .MongoDB is a product between a relational database and a non-relational database, the most versatile of the non-r

Install Scala and Spark in CentOS 1. Install Scala Scala runs on the Java Virtual Machine (JVM). Therefore, before installing Scala, you must first install Java in linux. You can go to my article http://blog.csdn.net/xqclll/article/details/54256713to continue without installing the SDK. Download the

Java and Scala environment configuration in Linux Recently, I have been studying a project on "natural language processing". In this project, we need to use Spark for programming. The Spark kernel is developed by the Scala language. Therefore, before using Spark, We must configure Scala and Scala runs on the JVM. There

The neophyte ' s Guide to Scala part 12:type ClassesOver the past two weeks, we have discussed some functional programming techniques that keep us dry and flexible, in particular function combinations, the application of partial functions, and currying. Next, I'll continue to discuss how to make your code as flexible as possible.However, this time we will not discuss how to use a function as a class object for this purpose, but instead use the type sy

Quick StartThis article describes how to use scala, java, and python to compile a spark click Mode Program. First, you only need to successfully build Spark on a machine. Practice: Enter the Spark root directory and enter the command: $ sbt/sbt package(Because of the Great Firewall of tianchao, the mainland China cannot succeed, unless you can smoothly flip the wall). If you do not want to climb the wall, you can download the pre-compiled Spark, spark

1. PreparationThis article focuses on how to build the Spark 2.11 stand-alone development environment in Ubuntu 16.04, which is divided into 3 parts: JDK installation, Scala installation, and spark installation. JDK 1.8:jdk-8u171-linux-x64.tar.gz Scala 11.12:scala 2.11.12 Spark 2.2.1:spark-2.2.1-bin-hadoop2.7.tgz It is important to note that

"Statement" The content of this post is copy, the source is the stack overflow.It has several meanings in Scala and all related to its mathematical meaning as implication. In a value, it introduces a function literal, or lambda. e.g. the bit inside the curly braces inList(1,2,3).map { (x: Int) => x * 2 } In a type, with symbols on both sides of the arrow (e.g. a = t , (b) + t , (a,b,c) = + T , etc.) It's sugar for function, that's, A Funct

scala-02 function definition, Process control, exception handlingFirst, theScala function definition:( The package is imported by default when the Scala function is defined)(1)val: variable (constant) similar to final type in Java 1, basic format: val variable name: variable type = value 2, where variable types can be omitted and can be automatically identified3, variable cannot be assigned, modifyvar

Lesson 2nd: Scala's object-oriented mastery and spark source readingContents of this issue:1 Scala's class, object in real combat2 abstract classes and interfaces in Scala3 comprehensive case and spark source code analysisOne: Define ClassClass hiscala{private var name = "Spark"Def sayname () {println (name)}def getName = Name}In Scala, a variable is the same as a method in a class and can be assigned directly to a method.There is a big difference bet

Scala multi-inheritance, constructor execution order, AOP implementation Trait implementations of multiple inheritance: Scala interfaces can inherit specific classes, trait interfaces can implement multiple inheritance, and a class can inherit a particular class, which can be mixed in after inheritance, the implementation of an interface Multi-inheritance constructor execution order: The ex

First-class functionsScala's functions are the first-class functions (first-class function). Not only can you define and invoke functions, you can also write them as anonymous literals (literal) and pass them as values.The function literal is compiled into the class and instantiated at run time as a function value. What do you mean? The essence of a function is an instance of a class. a function is a collection of attributes, and any function value is an instance of a class that extends one of s

CharacteristicsThe Java interface in Scala is trait (feature). It's actually more powerful than the interface. Unlike interfaces, it can also define the implementation of properties and methods. Features in Scala are used to serve the modularity of a single-purpose functional module. Scala is designed to meet the functional requirements of various applications by

The name of a function language comes from the concept that the program behavior should be like a mathematical function; in other words, given a set of inputs, the function should always return the same output. This not only means that each function must return a value, but also means that from one call to the next call, the function must not have an intrinsic State in nature ). This kind of stateless concept (in the function/object field, it is always an object by default ), it is the main reas

Although the underscore in the previous example replaces only a single argument, you can also use an underscore to replace the entire argument list. For example, write println (_), or better yet you can write println _. Here is an example: someNumbers.foreach(println　_) Scala sees this short form as directly as you enter the following code: someNumbers.foreach(x　=>　println(x))　 Therefore, the underscore in this example is not a placeholder for a s

To this chapter, the examples of all function texts refer only to the arguments passed in. For example, (x:int) => x > 0, the only variable used by the function body, x > 0, is x, which is defined as a function argument. However, you can also refer to variables defined elsewhere: (x:int) => x + more//How much is it? function to add "more" to the reference, but what is more? From the point of view of this function, more is a free variable: variable, because the function text itself does not gi

Here is a typical decision to make if ... Else the general form of the structure is used in most programming languages: If statement: The If statement consists of a Boolean expression followed by one or more statements. Grammar: Syntax for an IF statement: if (boolean_expression) { Statements'll execute if the Boolean expression is true } If the value of the Boolean expression is true, then the code module inside the IF statement is executed. If this is not the case, the first set of code if

It's really more and more like Scala, concise grammar, fresh style is my impression of Scala, it is really very convenient to use Scala programming, from Scala design ideas can also get a lot of inspiration, such as the following a fast sort of array of numbers (array[ Int]) method, have you ever thought of implementin

1, Scala and Java have 7 numeric types: int, short, long, byte, float, double, Boolean 7 kinds, but in Scala, these 7 types of values are classes, in Java, the basic type, Java, Data types are divided into basic types and reference types, which are not differentiated in Scala.2. The type of a variable or function in Scala