Even though Hibernate is called an object-relational mapper it's easy to select only a few properties instead of the whole mapped object. The hibernate query language (HQL) is very expressive. If you select some properties instead of the whole object, the call of
Query#list() returns a list of object arrays. Each field of the array contains one of the selected properties.
In my opinion iterating over lists of Object is verbose and error-prone because processing the result-list is directly dependant on the sequence of selected properties in the hql string. If you change the query string you have to change the sourcecode as well. Did I mention how expressive HQL is? :) Check out the following snippet:
Instead of returning arrays this query will return a list of maps each containing entries with aliases (the keys) to selected values. Actually it's possible to let Hibernate return partially loaded entities instead of maps containing the properties of interest. Check out the following example:
This query will return lists of customers assuming there is an appropriate constructor.
You should really pay attention with this approach of partially loaded entities because updating these entities could lead to accidently loosing data.