Question

我认为一旦通过伴侣对象创建了该类的对象，我就可以调用类的方法。但我无法做到这一点。以下是我的代码：

class Employee(val id: Int, val initialBalance: Int) {
  val message = println("Object created with Id: " + id + " balance: " + initialBalance)

  def printEmployeeDetails = "Id: " + id + " InitialBalance: " + initialBalance
  override def toString = "Id: " + id + " InitialBalance: " + initialBalance
}

object Employee {
  private var id = 0

  def apply(initialBalance: Int) {
    new Employee(newUniqueId, initialBalance)
  }

  def newUniqueId() = {
    id += 1
    id
  }

}

object testEmployee extends App {
  val employee1 = Employee(100)
  employee1.printEmployeeDetails  //getting error, why?
  println(employee1)    // This line is printing (), why?
  val employee2 = Employee(200)
  println(employee2)    // This line is printing (), why?
}

朋友们，你能帮我理解为什么会这样吗？感谢。

Answer 1

我明白了!!问题在于：

def apply(initialBalance: Int) {
    new Employee(newUniqueId, initialBalance)
}

我错过了等号，这就是为什么我错过了对象链接，即使它已经被创建了。现在更改代码是：

def apply(initialBalance: Int) = {
    new Employee(newUniqueId, initialBalance)
}

现在工作得非常好。感谢。

不会从Companion对象调用覆盖toString方法

1 个答案: