scala入门

val与var

• val为常量名
• var为变量名

数据类型

• Byte/Char
  Short/Int/Long/Float/Double
  Boolean
• 数字默认是Double类型，1.1为Double，1.1f为Float
• 类型转换：10.asInstanceOf[Double]
• 判断类型：10.isInstanceOf[Int]

lazy

lazy val a = 1，一般用在耗时计算或者网络请求上面

import scala.io.Source._
lazy val info = fromFile("/User/admin/Desktop/hello.txt").mkString

当使用info常量的时候，才会调用fromFile的方法

开发工具

• idea
• 下载idea的scala插件
• maven依赖

<dependency>
  <groupId>org.scala-lang</groupId>
  <artifactId>scala-library</artifactId>
  <version>${scala.version}</version>
</dependency>

• 代码编译

<plugin>
  <groupId>net.alchim31.maven</groupId>
  <artifactId>scala-maven-plugin</artifactId>
  <version>3.2.1</version>
  <executions>
    <execution>
      <id>compile-scala</id>
      <phase>compile</phase>
      <goals>
        <goal>add-source</goal>
        <goal>compile</goal>
      </goals>
    </execution>
    <execution>
      <id>test-compile-scala</id>
      <phase>test-compile</phase>
      <goals>
        <goal>add-source</goal>
        <goal>testCompile</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <recompileMode>incremental</recompileMode>
    <scalaVersion>${scala.version}</scalaVersion>
    <args>
      <arg>-deprecation</arg>
    </args>
    <jvmArgs>
      <jvmArg>-Xms64m</jvmArg>
      <jvmArg>-Xmx1024m</jvmArg>
    </jvmArgs>
  </configuration>
</plugin>