A string constant identifies the specific event, and you can have one or more constants in each event class.

一个字符串常量识别一个特定事件，一个事件类中可以有一个或多个常量。

youdao

A string constant identifies the specific event, and you can have one or more constants in each event class.

一个字符串常量识别一个特定事件，一个事件类中可以有一个或多个常量。

youdao