Omitting the constructor argument list and enclosing parentheses is equivalent to specifying an empty argument list.

省略构造函数参数列表和封闭的圆括号等价于指定一个空参数列表。

youdao

That's an empty argument if there ever was one.

FORBES: No Shame

The court heard Ayre threw the empty glass at Ms Richards while they were at the Flying Horse pub in September, during an argument over the amount for time he spent with her boyfriend.

BBC: Christopher Ayre jailed for 'horror movie' glass attack