Scala的基础用法 和 Java相对应学习（二）变量、循环、语法

一、配置相关环境

1.增加项目

在idea里面创建新的maven项目

2. 在pom文件中增加依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>bigdatascala</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>scala</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
<--scala语言的三个包-->
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.11.12</version>
        </dependency>

        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-compiler</artifactId>
            <version>2.11.12</version>
        </dependency>

        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-reflect</artifactId>
            <version>2.11.12</version>
        </dependency>
　　　　　　<--导入MySQL的依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
　　　　　　<--解析json工具-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.79</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>

            <!-- Java Compiler -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>

            <!-- Scala Compiler -->
            <plugin>
                <groupId>org.scala-tools</groupId>
                <artifactId>maven-scala-plugin</artifactId>
                <version>2.15.2</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

        </plugins>
    </build>
</project>

二、Scala 用法 （变量、字符串、拼接、循环、数组）

/*
def: scala中定义方法的关键字
main: 方法名
args：Array[String]方法的参数
      args：参数名
      Array[String] 参数类型
      String : 泛型
Unit: 相当于Java中的void
 */
//object 理解为单例对象，相当于Java中的给方法增加static静态关键字
object Demo1 {
  def main(args: Array[String]): Unit = {
    println("hello")

    //变量
    val a: String = "0"
    val b = 13
    val flag = true
    var c = 77
    c = 78
    println(a.getClass)
    println(flag.getClass)
    println(a, b, c)

    //字符串

    val value: String = "string,block,var,char,int,long,double,long,float,boolean"
    println(value.mkString(" "))
    val s3: Array[String] = value.split(",")
    //增强for 循环遍历数组
    for (elem <- s3) {
      print(elem)
      print("\t")
    }

    println(" ^*^ " * 30)
    val str: String = "java,hadoop,spark"
    val s2: Array[String] = str.split(",")
    println(s2.mkString("|"))
    println(" ^*^ " * 20)
    //字符串拼接
    val w = "我" + "是" + "最棒" + "的"
    println(w)
    val builder = new StringBuilder
    builder.append("java")
    builder.append("java1")
    builder.append("java2")
    builder.append("java3")
    println(builder)
    val str2 = s"$a,$b,$c,$flag"
    println(str2)
    println("---+++" * 30)
    //数组
    val ints: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 0)
    println(ints(5))
    println(ints mkString ".")
    ints(5) = 55
    println("-----" * 10)
    for (t <- ints) {
      print(t)
      print("|")
    }
    println("\r\n")
    //if  else 条件语句
    val scanner = new Scanner(System.in)
    print("请输入你要输入的年龄：")
    val i: Int = scanner.nextInt()
    if (i >= 18) {
      println("您已成年！")
    } else {
      println("对不起您未成年！！禁止未成年人进入网吧！请您成年后再过来")
    }

    //循环
    val array: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9)
    var j = 0
    while (j < array.length) {
      println(array(j))
      j += 1

    }
    println(".............")
    for (elem <- array) {
      println(elem)
    }
    //
  }
}