kotlin builder模式写法

class Person private constructor(builder: Builder) {

    internal var name: String? = null

    init {
        name = builder.name
    }


    class Builder {
        internal var name: String? = null

        fun name(name1: String): Builder {
            name = name1
            return this
        }

        fun build(): Person {
            return Person(this)
        }
    }
}

使用如果java用法一样 

Person.Builder().name("张三").build()