Java Hibernate query.list() 方法返回空列表而不是空值
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Hibernate query.list() method is returning empty list instead of null value
提问by Reddy
When there are no rows, both query.list()and criteria.list()are returning emptylist instead of a nullvalue.
当没有行时，query.list()和criteria.list()都返回空列表而不是null值。
What is the reason behind this?
这背后的原因是什么？
采纳答案by Péter T?r?k
The reason is not to force null checks in client code, in consistency with Effective Java 2nd Edition, Item 43: Return empty arrays or collections, not nulls.
原因是不强制在客户端代码中检查空值，与Effective Java 2nd Edition 的Item 43: Return empty arrays or collections, not nulls 一致。
This makes the client code simpler and less error-prone (and most likely the method implementation as well).
这使得客户端代码更简单，更不容易出错（很可能也是方法实现）。
The null-return idiom is likely a holdover from the C programming language, in which array lengths are returned separately from actual arrays. In C, there is no advantage to allocating an array if zero is returned as the length.
null-return 习惯用法可能是 C 编程语言的保留，其中数组长度与实际数组分开返回。在 C 中，如果返回零作为长度，则分配数组没有任何优势。
回答by Sjoerd
It is consistant: a list is returned with all results, whether there are any or not.
它是一致的：返回一个包含所有结果的列表，无论是否有结果。
