Java泛型：非静态类型变量T不能从静态上下文中引用 [英] Java Generics: non-static type variable T cannot be referenced from a static context

问题描述

 界面A< T> {
 
 interface B {
 //结果在非静态类型变量T中不能
 //从静态上下文中引用
 T foo（）; 
} 
 
} 
  

为什么T从AB引用时看起来是静态的？

解决方案

接口的所有成员字段默认为 public ， static 和 final 。

默认情况下，内部接口默认为 static ，您不能从静态字段引用 T 或方法。

因为 T 实际上与一个类的实例相关联，如果它与一个静态字段或与类关联的方法，那么它就没有任何意义了。

interface A<T> {

    interface B {
       // Results in non-static type variable T cannot
       // be referenced from a static context
       T foo(); 
    }

}

Is there anyway round this? Why is T seen as static when referenced from A.B?

解决方案

All member fields of an interface are by default public, static and final.

Since inner interface is static by default, you can't refer to T from static fields or methods.

Because T is actually associated with an instance of a class, if it were associated with a static field or method which is associated with class then it wouldn't make any sense

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