相关疑难解决方法(0)

想象一下这段简单的代码:

    class Constructor() {
  var string: String = _

  def this(s: String) = {this() ; string = s;}

  def testMethod() {
    println(string)
  }

  testMethod
}

object Appl {
  def main(args: Array[String]): Unit = {
    var constructor = new Constructor("calling elvis")
    constructor = new Constructor()
 }
}

结果是

null
null

我想成为

calling elvis
null

怎么做到这一点？在创建对象后我无法调用方法testMethod.

麻子

我有以下程序：

 class Rational(n: Int, d: Int) {
  require(d != 0)
  private val g = gcd(n.abs, d.abs)
  val numer = n / g
  val denom = d / g
  def this(n: Int) = this(n, 1)
  def this(s: String) = {
    val regex: Regex = "^([+-]?(\\d+|\\d*\\.?\\d+)|\\d*\\/?\\d+)$".r
    if (!regex.matches(s)) throw new NumberFormatException()
    val input: Array[String] = s.split("\\.|\\/")
    val num: Int = input(0).toInt
    if (input.length equals 1)
      this(num, 1) // problem here
    else
      this(num, input(1).toInt) // problem here
  }
}

我尝试用一​​些逻辑创建构造函数。但是，我不能因为

“Rational”不带参数

有什么问题？