Original
Class references
Sometimes operations are performed
on a class itself, rather than on instances of a class (that is, objects). This
happens, for example, when you call a constructor method using a class
reference. You can always refer to a specific class using its name, but at
times it is necessary to declare variables or parameters that take classes as
values, and in these situations you need class-reference types.
See also
译文
类引用
有时类的操作作用于其自身，这不同于作用于类的实例（即对象）。例如，当用类引用调用构造器方法时。对于这样的情况，总是可以明确指定要用的类的名称，但有时必需声明变量或参数把类作为值处理，并且这种情况下需要类引用类型（class-reference types）。