scala odersky

(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

Mappings and tuples Summary :A classic programmer's famous saying is: "If there is only one data structure, then use a hash table." A hash table , or more generally, a mapping , is one of the most flexible data structures. A map is a collection of key/value duality . Scala has a common term: tuples, which are aggregates of N objects, do not necessarily have the same type . duality is simply a n=2 tuple, and tuples are especially useful for

Tag: Spark installs Scala1. Download SparkHttp://mirrors.cnnic.cn/apache/spark/spark-1.3.0/spark-1.3.0-bin-hadoop2.3.tgz2. Download ScalaHttp://www.scala-lang.org/download/2.10.5.html3. Install ScalaMkdir/usr/lib/scalaTAR–ZXVF scala-2.10.5.tgzMV Scala-2.10.5/usr/lib/scala4. Set Scala pathVim/etc/bashrcExport scala_home=/usr/lib/

Scala supports associative mappings, such as a key-value pair that can be represented by (key, value) All types in Scala are objects, including basic data types The case statement in Scala is used to determine the received message, which is more than the switch...case in Java ... More focusedreceive{Case msg = action ()} The

In the previous chapter we introduced and then used the interpreter to write simple Scala code, and here's how to write a Hello word! using eclipse Open Eclipse. Create a new Scala Project. The first new words should be in other, name casually, then create a new Scala Object named "HelloWorld". Unlike Scala and Java, t

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 + much/more. 51CTO Editorial Recommendations: A special topic in Scala programming languages function to add "more" to the reference, but what is more it. From

=${java_home}/bin:$PATH 5 Execute java-version and javac-version if it can appear the instructions shown in Java installation complete　　Step Two: Install the Scala https://scala-lang.org/download/page to download1, wget https://downloads.lightbend.com/scala/2.12.6/scala-2.12.6.tgz2, unzip TAR-ZXF

* @param spark*/ Private Static voidDynamictransform (Sparksession Spark) {Javardd"StuInfo.txt"). Javardd (); Javardd{string[] parts= Line.split (","); String Sid= parts[0]; String sname= parts[1]; intSage = Integer.parseint (parts[2]); returnrowfactory.create (SID, Sname, Sage ); }); ArrayListNewArraylist(); Structfield Field=NULL; Field= Datatypes.createstructfield ("Sid", Datatypes.stringtype,true); Fields.Add (field); Field= Datatypes.createstructfi

Brief introductionThere are no enumeration types in Scala, but the enumeration class is provided in the standard class library to produce enumerations. After extending the enumeration class, call the value method class to initialize the possible values in the enumeration.The inner class value is actually an abstract class, and the real creation is Val. Because it is actually Val, you can pass in the ID and name for value. If not specified, the ID is a

Scala Arrays and lists:Import Scala.collection.mutable.ArrayBufferimport scala.collection.mutable.Bufferobject arraylearning {def main ( Args:array[string]): Unit = {//usezipunzip//listops//arrayops//arraybufferops} private def Usezipunzip = {//zip and unzip Val nums = List (1, 2, 3, 4) Val chars = List (' A ', ' B ', ' C ', ' d ') val combinlist = Nums.zi P (chars) println (combinlist) println (Combinlist.unzip)} private def arraybufferops = {//crea

The Withprintwriter method shown in the previous section differs from the built-in control structure of the language, such as if and while, where the code with the braces is parameterized. The Withprintwriter method requires a parameter of type PrintWriter. This parameter is displayed in the "writer =>" way: Withprintwriter (file) { writer => writer.println (new java.util.Date) } However, if you want to implement something more like if or while, there is no value to pass the code between the

At the time of writing, the summer is coming to an end, the new school year is about to begin, and Twitter's servers are constantly popping up with updates released by the world's web bugs and non-web bugs. For many of us in North America, from beach parties to football, from outdoor entertainment to indoor projects, all sorts of ideas are pouring in. To keep up with the situation, it is time to revisit Scitter, the Scala client library that is used t

Label:Read Oracle data in Scala After adding the Oralce jar package Package cn.bigdata.scala.oracle Import java.sql.{ DriverManager, Connection, ResultSet} object Connectoracle { val user= "Youname" val password = "Youpwd" val conn_str = "Jdbc:oracle:thin: @ip: 1521:database"; println (CONN_STR) def main (args:array[string]): Unit ={ //classof[com.mysql.jdbc.driver] Class.forName ("Oracle.jdbc.OracleDriver")//.newinstance

I. Fixed-length arraysIf you need an array of the same length, you can use the array in Scala. Val nums = new Array[int] (10)val s = Array ("Hello", "World")Two. Variable-length array: array buffering 1. val b = Arraybuffer[int] () 2. Append elements B + = (1,2,3,4,5) 3. Append any set b ++= Array (8,13,21) 4. Removal of the last 5 elements b.trimend (5) 5. Inserting elements B.insert (2,6) 6. Insert any number of elements