How can I map Optional to another Optional if not present? [duplicate]

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Category:Languages

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I have this Java 8 code:

public Optional<User> getUser(String id) {     Optional<User> userFromCache = cache.getUser(id);     if (userFromCache.isPresent()) {         return userFromCache;     }     return repository.getUser(id); } 

It works fine but I'm wondering how can I chain the call to not to use if. I have tried with orElseGet but it doesn't allow to return another Optional<User> but a User.

I want something like this:

Optional<User> userFromCache = cache.getUser(id)     .orElseGet(() -> repository.getUser(id)); 

 


Since Java 9, there is Optional.or. It accepts a supplier for another Optional.

return cache.getUser(id).or(() -> repository.getUser(id)); 

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