Java Interface Inheritance and Extending

Imagine you are working on a mature product and a new search feature is requested that is required for 50% of your produ开发者_JAVA百科ct. Now assuming you have an established interface inheritance relationship with SomeDao that you don't want to break...

public interface MoneyDao 
    extends SomeDao<MoneyEntity>
{
    //Operation common in much of the application
    List<MoneyEntity> findByCriteria(MoneyCriteria criteria);     
}

...is there a way to expose the method 'findByCriteria(..)' without repeating it in all the other places similar to MoneyDao where it's required in a cleaner way?

Bare in mind I want to avoid casting in to a new type where its used and modifying SomeDao if at all possible.

Regards, James

Can you break the findByCriteria into its own interface and extend it in MoneyDao? Something like this:

public interface MoneyDao 
    extends SomeDao<MoneyEntity>, MoneyFinder
{
}

public interface MoneyFinder
{
    //Operation common in much of the application
    List<MoneyEntity> findByCriteria(MoneyCriteria criteria);     
}

Now your class(es) implementing MoneyDao don't need to change, but you can pass around just the findByCriteria using MoneyFinder.

Its all depends on if you want a class that is searchable and is a Dao, in other words its if your Searchable class must also be a Dao. If its this case I would use a generic approach to make your Dao Searchable.

interface SearchableDao<Entity, Criteria> extends SomeDao<Entity> 
{
    List<Entity> findByCriteria(Criteria criteria);
}

Now your class can be a simple Dao or a SearchableDao. SearchableDao is also a simple Dao.

class MoneyDao implements SearchableDao<MoneyEntity, MoneyCriteria> 
{
    List<MoneyEntity> findByCriteria(MoneyCriteria criteria) {...} 
}