scala – 从辅助构造函数初始化val

发布时间：2020-12-16 18:42:46 所属栏目：安全来源：网络整理

导读：我有以下课程代表一些金额： class Money(initDollars: Int,initCents: Int){ require (initDollars = 0 initCents = 0) private def this(positive: Boolean,initDollars: Int,initCents: Int) = { this(initDollars,initCents) //this.positive = positive

我有以下课程代表一些金额：

class Money(initDollars: Int,initCents: Int){

  require (initDollars >= 0 && initCents >= 0)

  private def this(positive: Boolean,initDollars: Int,initCents: Int) = {
    this(initDollars,initCents)
    //this.positive = positive
  }

  val positive: Boolean = true
  val dollars = initDollars + initCents/100
  val cents = initCents % 100
  private val totalAmount = dollars * 100 + cents

  def unary_- = new Money(!positive,dollars,cents)
}

object Money{
  def apply(initDollars: Int,initCents: Int) = new Money(initDollars,initCents)
}

金额也可能是负数,我想像这样创建它：

val am = -Money(1,20)

所以我想从辅助构造函数初始化val positive,但我不能这样做,因为它重新分配给val.我也无法在辅助构造函数的参数列表中添加val.有人可以帮忙吗？

解决方法

反过来做.

class Money private (pos: Boolean,initCents: Int) {

  require (initDollars >= 0 && initCents >= 0)

  def this(initDollars: Int,initCents: Int) = {
    this(true,initDollars,initCents)
  }

  val positive: Boolean = pos
  val dollars = initDollars + initCents/100
  val cents = initCents % 100
  private val totalAmount = dollars * 100 + cents

  def unary_- = new Money(!positive,cents)
}

（编辑：李大同）

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