Sometimes you don't want to initialize a large collection, but still need some information about it (like its size) or a subset of the data.

有时候，你并不需完全实例化整个大的集合，仅需要了解它的部分信息（例如其大小）、或者集合的部分内容。

youdao

Sometimes you don't want to initialize a large collection, but still need some information about it (like its size) or a subset of the data.

有时候，你并不需完全实例化整个大的集合，仅需要了解它的部分信息（例如其大小）、或者集合的部分内容。

youdao