Question

所以我有这个变量currentPartNumber，它开始等于0.我想要发生的是在我的函数中，如果变量等于零，则将其更改为1并打印出文本。我的第二个函数也是一样 - 如果我的第一个函数中的变量更改为1并且等于1，我希望变量更改为2，打印出文本。

问题是：如何使用我想要的每个函数调用来更改变量？

var currentPartNumber = 0

def roomOne():Unit = {
   if (currentPartNumber < 1) {
      var currentPartNumber = 1
      println("You now have parts 1 of 4.")
     } else {
      println("This part cannot be collected yet.")
   {
   }


def roomTwo():Unit = {
   if (currentPartNumber = 1) {
      var currentPartNumber = 2
      println("You now have parts 2 of 4.")
     } else {
      println("This part cannot be collected yet.")
   {
   }

Answer 1

不要遮蔽变量：从函数内部删除var。

var关键字声明新成员/变量。在这种情况下，名称与阴影来自外部范围的变量相同。因此，赋值（作为声明的一部分）对外部变量没有影响。

// no var/val - assignment without declaration
currentPartNumber = 2

另见：

Answer 2

在currentPartNumber和roomOne()可以访问和修改它的类中声明roomTwo()。

class Parts{
  var currentPartNumber = 0

  def roomOne():Unit = {
    if (currentPartNumber < 1) {
      currentPartNumber = 1
      println("You now have parts 1 of 4.")
    } else {
      println("This part cannot be collected yet.")
    } 
  }  

  def roomTwo():Unit = {
    if (currentPartNumber == 1) {
       currentPartNumber = 2
       println("You now have parts 2 of 4.")
     } else {
      println("This part cannot be collected yet.")
     }
   }
}



scala> :load Parts.scala
Loading Parts.scala...
defined class Parts
scala> var parts = new Parts
parts: Parts = Parts@5636a67c
scala> parts.currentPartNumber
res0: Int = 0
scala> parts.roomOne
You now have parts 1 of 4.
scala> parts.roomTwo
You now have parts 2 of 4.

如何在scala更改中创建变量？

2 个答案: