摘要： ######################### 高阶函数 ######################### scala> def sum(x: Int) = x + 1 sum: (x: Int)Int scala> println(sum(5)) 6 Lamda表达式 scala> val 阅读全文

摘要： scala> val number = Seq(20, 40, 60) number: Seq[Int] = List(20, 40, 60) scala> val numbers = (x: Int) => x * 2 numbers: Int => Int = <function1> scala 阅读全文

摘要： scala> val f: String => Int = arg => arg.toInt * 2 f: String => Int = <function1> scala> f res0: String => Int = <function1> scala> f("5") res1: Int = 阅读全文

摘要： package spark.demo object Demo { def main(args: Array[String]) { val m: Map[Int, String] = Map(3 -> "Python", 1 -> "Java", 2 -> "Scala", 6 -> "SQL") / 阅读全文

摘要： [root@centos00 ~]$ jps 7174 Kafka 7502 Jps [root@centos00 ~]$ PIDS=$(jps -lm | grep -i 'kafka.Kafka'| awk '{print $1}') [root@centos00 ~]$ kill -9 ${P 阅读全文

摘要： [root@centos00 ~]$ ./stop-kafka.sh -bash: ./stop-kafka.sh: /bin/sh^M: bad interpreter: No such file or directory 解决: 编码集Windows(CR LF)更改为Unix(LF) 阅读全文

摘要： 高阶函数的基本构成 def 方法名(函数名: (函数的参数类型) => 函数的返回值类型) { 处理的具体内容 } 案例 package com.spark.demo object HigherOrderFunction { def main(args: Array[String]): Unit = 阅读全文

摘要： /* Navicat MySQL Data Transfer Source Server : localhost Source Server Version : 50527 Source Host : localhost:3306 Source Database : mydb Target Serv 阅读全文

摘要： scala> val df = Seq(1.to(5).mkString(",")).toDF("number") df: org.apache.spark.sql.DataFrame = [number: string] scala> df.show(false) + + |number | + 阅读全文

摘要： /* Navicat MySQL Data Transfer Source Server : localhost Source Server Version : 50527 Source Host : localhost:3306 Source Database : mydb Target Serv 阅读全文