Life 4 J

文章列表連結Job

import(匯入) in scala

Import(匯入) 在 scala 有很多方法

最常用

import jason.playground._ 匯入 jason.playground package 底下的所有 classes and object, 包括 package object(package object 的所有 member 會以 static 方面匯入)

匯入特定 class 的 member

import jason.playground.JasonPhone._ 匯入 jason.playground.Jason 底下的所有 member

例子

package jason.playground

object JasonPhone {
  def name() = "Iphone 6"
}

package jason

import jason.playground.JasonPhone

package object playground {
  // static method to be imported into class
  def getName() = "Iphone 6 (from helper method)"

  // align to another object's method
  def nameFromPackageObject() = JasonPhone.name()
}

package jason.program

// this line import classes & object under jason.playground (not recurisly)
import jason.playground._;

// this line import "members" under jason.playground.JasonPhone
// ~ import static in Java
import jason.playground.JasonPhone._;

/**
  * Created by Jason on 1/20/16.
  */
object Main {
  def main(args: Array[String]): Unit = {
    println("I am using: " + JasonPhone.name()) // this is declared in JasonPhone.scala
    println("I am using: " + nameFromPackageObject()); // this is declared in package.scala
    println("I am using: " + name()); // this is a short cut with static import
  }
}
  • JasonPhone.name() 由匯入 jason.playground._ 而來
  • nameFromPackageObject() 由匯入 jason.playground._ 而來，是 package object 裡的 method
  • name() 由 static 匯入 jason.playground.JasonPhone._ 而來，不用打 JasonPhone 作為 prefix

Play Framework 匯入應用

val userForm = Form(
  mapping(
    "name" -> of[String],
    "age" -> of[Int],
    "email" -> of[String]
  )(User.apply)(User.unapply)
)

of 由匯入 play.api.data.Forms._ 得來, Forms 是一個 object 定義 helper methods