Static Fields Prohibited in Inner Classes: Rationale

Java prohibits the declaration of static fields and methods within inner classes (or ordinary inner classes) due to their inherent instance-dependent nature.

Inner classes, unlike static nested classes, are tied to他们封闭班级的实例。这意味着内部类的每个实例都与封闭类的特定实例都有独特的关联。结果，允许在内部类中允许静态字段在静态字段所属的实例中产生歧义。

此外，允许内部类中的静态字段与基于实例的依赖关系的原理相矛盾。 Since inner classes rely on instances of the enclosing class, it doesn't make sense for them to have static features, which are designed to operate independently of any instance.

class OuterClass {
  class InnerClass {
    static int i = 100; // compile error
  }
}

Clarity and consistency:

遵守设计原理：