kotlin 类继承的语法

写段测试代码：

open class Person { // 加open关键字，可以被子类继承
    open var name: String = ""
    open var age: Int = 0
    
    constructor(name: String, age: Int) {
        this.name = name
        this.age = age
    }
    
    override fun toString() : String {
        return "我是${name}, 年龄$age." //这里不能写this.name, this.age，不然会栈溢出。为啥？？
    }
}

class Daxia : Person {
    var kongfus: List<String> = listOf()
    var wuli: Int = 0
    
    constructor(name: String, age: Int, kongfus: List<String>, wuli: Int) : super(name, age) {
        this.kongfus = kongfus
        this.wuli = wuli
    }
    
    override fun toString() : String {
        return super.toString() + "我会的武功：${kongfus}, 我的武力值: $wuli"
    }
}

fun main() {    
    val zhouzhiruo =  Daxia("周芷若", 23, listOf("九阴真经"), 89)
    val tianboguang = Daxia("田伯光", 30, listOf("狂风刀法"), 81)
    val duanzhengchun = Daxia("段正淳", 42, listOf("一阳指"), 80)
    val jiumozhi = Daxia("鸠摩智", 40, listOf("小无相功", "少林七十二绝技", "少林易筋经", "火焰刀"), 96)
    
    println(zhouzhiruo.toString())
    println(tianboguang.toString())
    println(duanzhengchun.toString())
    println(jiumozhi.toString())
}

打印：

ok.