java - 扩展内部接口(interface)？

Question

我有一个简单的问题:

为什么 Eclipse 强烈要求实现这两个接口(interface)？

public abstract class Gateway implements IPlayerity, IItemity {
    public interface IPlayerity { ... }
    public interface IItemity { ... }
    // I...ity
}

我收到此错误消息:

IPlayerity cannot be resolved to a type

Answer 1

鉴于 JLS 的工作方式，您有一个无法解决的循环依赖(尽管我不确定在 JLS 的哪个位置记录了这一点)。

IPlayerity 和 IItemity 接口(interface)对 NestedInterfaces 类 header 定义不可见，因为它们在其中。我可以通过将您的程序更改为

来解决此问题

public class NestedInterfaces implements 
      NestedInterfaces.IPlayerity, NestedInterfaces.IItemity 
{
    public interface IPlayerity {}
    public interface IItemity {}
}

但是 Eclipse 给了我这个错误，这个错误更清楚了:

 Multiple markers at this line
 - Cycle detected: the type NestedInterfaces cannot extend/implement itself or one of its own member types
 - Cycle detected: the type NestedInterfaces cannot extend/implement itself or one of its own member types