Spark记录-Scala shell命令

1.scala shell命令

scala> :help

All commands can be abbreviated, e.g., :he instead of :help.

:edit <id>|<line>        edit history

:help [command]          print this summary or command-specific help

:history [num]           show the history (optional num is commands to show)

:h? <string>             search the history

:imports [name name ...] show import history, identifying sources of names

:implicits [-v]          show the implicits in scope

:javap <path|class>      disassemble a file or class name

:line <id>|<line>        place line(s) at the end of history

:load <path>             interpret lines in a file

:paste [-raw] [path]     enter paste mode or paste a file

:power                   enable power user mode

:quit                    exit the interpreter

:replay [options]        reset the repl and replay all previous commands

:require <path>          add a jar to the classpath

:reset [options]         reset the repl to its initial state, forgetting all session entries

:save <path>             save replayable session to a file

:sh <command line>       run a shell command (result is implicitly => List[String])

:settings <options>      update compiler options, if possible; see reset

:silent                  disable/enable automatic printing of results

:type [-v] <expr>        display the type of an expression without evaluating it

:kind [-v] <expr>        display the kind of expression's type

:warnings                show the suppressed warnings from the most recent line which had any

2.scala基本类型

3.常用特殊字符

\n 换行符，其Unicode编码为 (\u000A)
\b 回退符，其Unicode编码为 (\u0008)
\t tab制表符，其Unicode编码(\u0009)
\” 双引号，其Unicode编码为 (\u0022)
\’ 单引号，其Unicode编码为 (\u0027)
\ 反斜杆，其Unicode编码为(\u005C)

4.函数

5.类

//采用关键字class定义

class Person {

//类成员必须初始化，否则会报错

//这里定义的是一个公有成员

var name:String=null

}

附录：

import java.sql.{ Connection, DriverManager }

import java.util.{Date, Locale}

import java.text.DateFormat

import java.text.DateFormat._

object Mysql extends App {

 // def main(args: Array[String]): Unit = {

    // 访问本地MySQL服务器，通过3306端口访问mysql数据库

    val url = "jdbc:mysql://localhost:3306/mysql"

    //驱动名称

    val driver = "com.mysql.jdbc.Driver"

    //用户名

    val username = "root"

    //密码

    val password = "1"

    //初始化数据连接

    var connection: Connection = _

    try {

      //注册Driver

      Class.forName(driver)

      //得到连接

      connection = DriverManager.getConnection(url, username, password)

      val statement = connection.createStatement

      //执行查询语句，并返回结果

      val rs = statement.executeQuery("SELECT host, user FROM user")

      //打印返回结果

      while (rs.next) {

        val host = rs.getString("host")

        val user = rs.getString("user")

        println("host = %s, user = %s".format(host, user))

      }

    } catch {

      case e: Exception => e.printStackTrace

    }

    //关闭连接，释放资源

    connection.close

    //for循环

    var myArray: Array[String] = new Array[String](10);

    for (i <- 0 until myArray.length) {

      myArray(i) = "value is: " + i;

    }

    for (value: String <- myArray) {

      println(value);

    }

    for (value: String <- myArray if value.endsWith("5")) {

      println(value);

    }

  val now = new Date

  val df = getDateInstance(LONG, Locale.FRANCE)

  println(df format now)

  //}

  val greetStrings =new Array[String](3)

  greetStrings(0)="Hello"

  greetStrings(1)=","

  greetStrings(2)="world!\n"

  greetStrings.update(0,"Hello")

  greetStrings.update(1,",")

  greetStrings.update(2,"world!\n")

  for(i <- 0 to 2)

    print(greetStrings(i))

  val oneTwo = List(1,2)

  val threeFour = List(3,4)

  val oneTwoThreeFour=oneTwo ::: threeFour

  println (oneTwo + " and " + threeFour + " were not mutated.")

  println ("Thus, " + oneTwoThreeFour + " is a new list")

  //几种循环

  def printArgs ( args: Array[String]) : Unit ={

    var i=0

    while (i < args.length) {

      println (args(i))

      i+=1

    }

  }

  def printArgs1 ( args: Array[String]) : Unit ={

    for( arg <- args)

      println(arg)

  }

  def printArgs2 ( args: Array[String]) : Unit ={

    args.foreach(println)

  }

  //类与对象

  class ChecksumAccumulator{

    private var sum=0

    def add(b:Byte) :Unit = sum +=b

    def checksum() : Int = ~ (sum & 0xFF) +1

  }

  def gcdLoop (x: Long, y:Long) : Long ={

    var a=x

    var b=y

    while( a!=0) {

      var temp=a

      a=b % a

      b = temp

    }

    b

  }

}

巴特西

Spark记录-Scala shell命令

1.scala shell命令

2.scala基本类型

3.常用特殊字符

4.函数

5.类

附录：

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