如何在scala中访问内部类元素

Question

我有一个简单的内部类变量，如何在scala中访问它？

class Outer {
  class Inner {
    var x = 1
  }}


object Main {
  def main(args: Array[String]): Unit = {
    val o = new Outer
    val i = new o.Inner
    println(i.x)
  }
}

Answer 1

您可以简单地使用。member\u name访问scala中的变量。

scala> class Outer {
        class Inner {
          var x = 1 //it can be val which is immutable
        }}
defined class Outer

scala> val o = new Outer
o: Outer = Outer@358b0b42

scala> val i = new o.Inner
i: o.Inner = Outer$Inner@512f2c7d

scala> i.x
res13: Int = 1

由于您的示例将x定义为可变的，因此您可以更改x的值，

scala> i.x = 100
i.x: Int = 100

scala> i.x
res14: Int = 100

参见工作示例-https://scastie.scala-lang.org/prayagupd/C9k9an4ASdaISnohbYQBmA

如果你真的不需要Outer成为一个类，你可以将它定义为singleton，

scala> object Outer {
     |             class Inner {
     |               var x = 1 //it can be val which is immutable
     |             }}
defined object Outer

然后，简单实例化内部和访问变量，

scala> val inner = new Outer.Inner
inner: Outer.Inner = Outer$Inner@4bcdd11

scala> inner.x
res2: Int = 1

关于不在intellij上工作，文件|无效缓存/重启...应该工作