Java泛型类型参数隐藏 [英] Java generics type parameter hiding

问题描述

我定义了一个类：

  class Foo< I extends Bar&可比< I>> {
} 
  

编译器抱怨 I 被 I隐藏。我想第二次出现在定义中的 I 隐藏在第一个范围内，就好像变量 I 可以是分配给两种不同的类型。如何正确地做到这一点？

编辑：

这是一个内部类。完整的代码可以是：

  class Baz< I> {
 class Foo< I extends Bar&可比< I>> {
} 
} 
  

现在的问题是，如果我重新提名内我到 J ，我不确定 I 和 J 实际上是相同的类型。

解决方案

使内部类参数化：

  class Baz< I extends Bar&可比< I>> {
 class Foo {
} 
} 
  

（非静态嵌套）类， Baz 声明中定义的 I 仍然在 Foo ，因为每个 Foo 都会隐式引用其外部 Baz 实例。

I'm defining a class:

class Foo<I extends Bar & Comparable<I>> {
}

the compiler is complaining about I being hidden by I. I guess the second time I appears in the definition is hiding in scope the first one, as if variable I could be assigned to two different types. How to do it correctly?

Edit:

this is an inner class. the full code can be:

class Baz<I> {
    class Foo<I extends Bar & Comparable<I>> {
    }
}

now the problem is that if I re-nominate inner I to J, i'm not sure that I and J are actually the same types.

解决方案

Don't make the inner class parameterized:

class Baz<I extends Bar & Comparable<I>> {
   class Foo {
   }
}

As an inner (non-static nested) class, I as defined in the Baz declaration will still have meaning in Foo, since every Foo will have an implicit reference to its outer Baz instance.

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