Ask HN: Designing via Interface in Java?

2 points by antoaravinth 9y ago ↗ HN

Hi, Often I see experienced Java developers asking us to develop the system using Interfaces rather than starting with classes. Yes, I do create interfaces, I know whats its usecases are etc. However the term "design your system using interfaces" is somewhat confusing to me. Is it a pattern for designing robust application in Java world? How should one learn it?

If so are there any online books / blogs regarding the same?

Note: I had already asked the question in Java Subreddit, but I want to get HN community thoughts as well.

1 comment

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davelnewton 9y ago ↗

I'm not clear on what the conceptual hurdle is.

Of course it's a common pattern--that doesn't mean it's always necessary. It does make a lot of things easier, like testing, etc.

It's the same thing as declaring your vars as `List` or `Collection` instead of `ArrayList`. If you do the same thing in your system you give yourself much more flexibility.