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Comment by asddubs | Hacker News Reader

I actually quite like checked exceptions, and miss them in other languages. My biggest gripe with exceptions is that a few calls deep, you can no longer tell whether calling something might throw or not, and what type of exception it might potentially throw.

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Checked exceptions are a leaky concept in Java. The Java type system has no union types so you can not have a generics method that abstract more than one exception.

That's why Stream::map can not capture the checked exceptions properly.

Definitely they have shortcomings in Java but throwing the concept out entirely is a bummer. It creates a whole shadow type system where all bets are off.

Yes! The problem with the Java implementation of checked exceptions is the inheritance hierarchy, which encourages catching the broadest possible error.

I like checked exceptions in principle too, but Java's implementation of them is so bad that I hate them there. The first major mistake is that it doesn't support exception polymorphism (e.g., I wish you could pass a comparator to Arrays.sort that throws checked exceptions, and have that call to Arrays.sort itself then throw the same checked exceptions), and the second is that the standard library makes a bunch of exceptions checked that should be unchecked (e.g., IOException from close()).

Which is now commonly wrapped into UncheckedIOException.

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