final Fields

8.3.1.2. final Fields

A field can be declared final (§4.12.4). Both class and instance variables (static and non-static fields) may be declared final.

A blank final class variable must be definitely assigned by a static initializer of the class in which it is declared, or a compile-time error occurs (§8.7, §16.8).

A blank final instance variable must be definitely assigned and moreover not definitely unassigned at the end of every constructor of the class in which it is declared, or a compile-time error occurs (§8.8, §16.9).

 

 

 

 

 

参考：https://docs.oracle.com/javase/specs/jls/se17/html/jls-8.html#jls-8.3.1.2

#################################