单例对象（只有一个的对象）

object Person{
    private var lastId = 0
    def newpersonId() = {
    lastId +=1
    lastId
    }
}
printf("this frist person id is %d.\n",Person.newpersonId())
printf("this frist person id is %d.\n",Person.newpersonId())
printf("this frist person id is %d.\n",Person.newpersonId())

静态字段，每次调用用到的都是同一个对象的值

伴生对象

需要满足相同名字

class Person{  //这个玩意叫伴生类，两者的名字是一样的
    private val id = Person.newPersonId()   //调用了伴生对象中方法，相当于是同一个属性（静态方法）
    private var name =""
    def this(name : String){
        this()
        this.name = name
    }
    def info(){printf("this id of %s is %d.\n"name,id)}
}
object Person{
    private var lastId = 0
    private def newpersonId() = {  
    lastId +=1
    lastId
    }
    def main(args:Array[String]){
        val person1 = new Person("Ziyu")
        val person2 = new Person("Minxing")
        person1.info()
        person2.info()
    }
}

验证两者合二为一

class Person{  //这个玩意叫伴生类，两者的名字是一样的
    private val id = Person.newPersonId()   //调用了伴生对象中方法，相当于是同一个属性（静态方法）
    private var name =""
    def this(name : String){
        this()
        this.name = name
    }
    def info(){printf("this id of %s is %d.\n"name,id)}
}
object Person{
    private var lastId = 0
    def newpersonId() = {   //这里去掉了private
    lastId +=1
    lastId
    }
    def main(args:Array[String]){
        val person1 = new Person("Ziyu")
        val person2 = new Person("Minxing")
        person1.info()
        person2.info()
    }
}