一：内部类的作用对象：外部类对象

import scala.collection.mutable.ArrayBuffer

c1.students += jack

二：扩大内部类作用域：伴生对象

object Class {   class Student(val name: String) } class Class {   val students = new ArrayBuffer[Class.Student]   def register(name: String) = {     new Class.Student(name)   } } val c1 = new Class val leo = c1.register("leo") c1.students += leo val c2 = new Class val jack = c2.register("jack") c1.students += jack

三：扩大内部类作用域：类型投影

class Class {   class Student(val name: String)   val students = new ArrayBuffer[Class#Student]   def register(name: String) =  {     new Student(name)   } } val c1 = new Class val leo = c1.register("leo") c1.students += leo val c2 = new Class val jack = c2.register("jack") c1.students += jack

四：内部类获取外部类的引用

class Class(val name: String) { outer =>   class Student(val name: String) {     def introduceMyself = "Hello, I'm " + name + ", I'm very happy to join class " + outer.name   }   def register(name: String) =  {     new Student(name)   } } val c1 = new Class("c1") val leo = c1.register("leo") leo.introduceMyself