My question is fairly simple.. What is the closest ORM to ActiveRecord that I’d be able to find for Java?
In other words, in terms of thinking patterns and knowledge, with limted development time, what ORM should I use for Java, coming from a Rails + ActiveRecord background? Which one is both good enough and would be easy/quick enough to learn?
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ActiveRecord, the Ruby ORM, relies quite heavily on features of Ruby that are not available in Java, particularly the “method_missing” method and ability to create member variables dynamically. Implementations of Active Record, the pattern, on Java are therefore harder to work with than in Ruby. Typically, you have to accept one of the following shortcomings:
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fields of your object are accessed via a generic “get(fieldName)” method rather than directly, thus meaning you lose type safety, the primary benefit of using Java rather than Ruby, or
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you use generated code for your model classes, thus are restricted to having an “anemic model”, which many consider an antipattern.
For this reason, most Java ORMs use the Repository or Data Access Object patterns, which make it easier to avoid these problems when working in a static language. The Active Record pattern is most commonly used by hand-coded persistence code, rather than ORMs.
I would recommend learning how to use the Repository pattern; it is slightly more complex than Active Record, requiring one extra object per model class, but is more flexible in the long run.