Effective Java

Last week I read the third edition of Effective Java. It was of the must-read books stuck in my TO-READ list. And it was better than I expected!.

There were a lot of things I already knew. Obviously, I should have read it many years ago, and I wouldn’t have fallen into many mistakes Joshua Bloch mentions in the book. But I’ve read it now, after 10+ years writing Java programs… and still, there were some surprises, a fair share of new things!.

And here it is a noncomprehensive list of the 90 items, the ones that left me scratching my head:

• Item 31: Use bounded wildcards to increase API flexibility

The idea is, inside a public API of a library with generics, expose a bounded wildcard <E extends MyDomainClass> instead of a generic, like MyDomainClass. That way consumers of your library have more flexibility. This applies to classes, methods with input arguments and outputs. There is even a mnemonic to know which kind of bounded wildcard to use!

I have to say that most items in this chapter about generics taught me several things… especially the item about how to ignore casts and warnings 😳

• Item 36: Use EnumSet instead of bit fields

Ok… I didn’t know EnumSet existed. Enough said. I was even at a loss on how joining integer constants with | worked…

• Item 55: Return optionals judiciously

I had already read about the bad practice of using Optional as fields… but I hadn’t thought a lot about returning Optionals in a library and how it forces the users to deal with it. Food for thought.

• Item 69: Use exceptions only for exceptional conditions

I also supported it before reading the book but the book made me hate Checked Exceptions even more!

• Item 86: Implement Serializable with great caution

I’m not using Serializable a lot right now. But I used to do it… without knowing all the problems associated with it (I knew about serialization conflicts but not the security problems). After reading 7 or 8 items about Serialization, the book convinced me to not use it ever again. Eye opener.

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A quite interesting book, I recommend you to check it out if you already know Java and have a few years of experience with it, even if you only read the chapters/items that you like/want to learn more.

See you around! :D