scala 半生对象和半生类

object：半生对象object中的构造器在第一次调用执行一次，以后调用的话不会多次执行。object会有自己的构造方法，默认是没有参数的构造方法object放一些静态的成员或方法如SparkContext同时有类和object半生类和半生对象放在同一个文件夹中半生对象中有一个apply方法构造类的时候一般不用new Person（）而是不用newclass Person是object Person的半生类object Person是class Person的半生对象scala> /////////////////////scala> object Person{     |   println("scala")     |   var salary = 0.0     |   def getSalary = salary     | }defined module Personwarning: previously defined class Person is not a companion to object Person.Companions must be defined together; you may wish to use :paste mode for this.scala> Person.getSalary  --object名直接调用scala      --只打印一次，后面执行不打印res131: Double = 0.0scala> Person.getSalaryres132: Double = 0.0scala> /////////////////////scala> class Person{     |   println("scala in class...")     |   var salary = 0.1     |   def getSalary = salary     | }defined class Personwarning: previously defined object Person is not a companion to class Person.Companions must be defined together; you may wish to use :paste mode for this.scala> Person.getSalary  --还是上面object的调用res133: Double = 0.0scala> val p = new Person   --class只能new出来使用scala in class...p: Person = Person@2059a675scala> p.getSalaryres134: Double = 0.1