Question

Scala新手在这里。我对以下代码抛出异常的原因感到很困惑。我知道Function1[Int, Int]有一个需要定义的类型为apply的抽象Int => Int方法。以下oddfunc不是这样做的吗？为什么没有x(3)调用apply中定义的具体oddfunc方法？

Welcome to Scala version 2.11.5 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_25).
Type in expressions to have them evaluated.
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scala> trait oddfunc extends Function1[Int,Int] {
 | def apply(a: Int): Int = a+3
 | }
defined trait oddfunc

scala> val x = new oddfunc{}
x: oddfunc = <function1>

scala> x(3)
java.lang.AbstractMethodError: $anon$1.apply$mcII$sp(I)I
  at oddfunc$class.apply(<console>:8)
  at $anon$1.apply(<console>:8)
  ... 43 elided

Answer 1

这看起来像是在2.11.4和2.11.5之间引入Scala编译器的错误。我降级到Scala 2.11.4以确定是否修复了它并确实如此。

Welcome to Scala version 2.11.4 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_25).
Type in expressions to have them evaluated.
Type :help for more information.

scala> trait oddfunc extends Function1[Int,Int] {
     | def apply(a: Int): Int = a+3
     | }
defined trait oddfunc

scala> val x=new oddfunc{}
x: oddfunc = <function1>

scala> x(3)
res0: Int = 6

如何创建抽象Function1特征的实现

1 个答案: