java - Kotlin 基础继承方案

Question

如何使用 owner 和 balance 的初始值创建新的 SavingAccount

open class BankAccount(val owner: String = "Long John Silver", private var balance: Double = 0.00) {

    constructor (amount: Double) : this() {
        this.balance = amount
    }
    fun deposit(amount: Double){
        this.balance += amount
    }
    fun withdraw(amount: Double){
        this.balance -= amount
    }
    fun getBalance(): Double{
        return this.balance
    }
}

还有子类

class SavingAccount(val increasedBy: Double = 0.05): BankAccount(){

    fun addInterest(): Unit{
        val increasedBy = (this.getBalance() * increasedBy)
        deposit(amount = increasedBy)
    }
}

主要是

fun main(args: Array<String>) {

    val sa = SavingAccount();// how to do this SavingAccount("Captain Flint", 20.00)
    println(sa.owner)
    println(sa.owner)
}

如何在没有默认值的情况下为新用户创建 SavingAccount？

Answer 1

您可以使用普通的构造函数参数(因此没有属性)实现它，并将它们传递到您的 BankAccount

class SavingAccount(owner: String,
        balance: Double,
        val increasedBy: Double = 0.05
): BankAccount(owner, balance) {

}

SavingAccount 的默认值可以定义为类似于 BankAccount:

class SavingAccount(owner: String = "Default Owner",
        balance: Double = 0.0,
        val increasedBy: Double = 0.05
): BankAccount(owner, balance) {

}