Vanilla Java
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@SneakyThrows can be used to sneakily throw checked exceptions without actually declaring this in your method's throws
clause. This somewhat contentious ability should be used carefully, of course. The code generated by lombok will not ignore, wrap, replace,
or otherwise modify the thrown checked exception; it simply fakes out the compiler. On the JVM (class file) level, all exceptions, checked or not,
can be thrown regardless of the throws clause of your methods, which is why this works.
CAREFUL: Unlike other lombok transformations, you need to put lombok.jar on your classpath when you run your program.
Common use cases for when you want to opt out of the checked exception mechanism center around 2 situations:
Runnable - whatever exception propagates out of your run() method,
checked or not, it will be passed to the Thread's unhandled exception handler. Catching a checked exception and wrapping it
in some sort of RuntimeException is only obscuring the real cause of the issue.new String(someByteArray, "UTF-8"); declares that it can throw an
UnsupportedEncodingException but according to the JVM specification, UTF-8 must always be available. An
UnsupportedEncodingException here is about as likely as a ClassNotFoundError when you use a String object,
and you don't catch those either!
Be aware that it is impossible to catch sneakily thrown checked types directly, as javac will not let you write a catch block
for an exception type that no method call in the try body declares as thrown. This problem is not relevant in either of the use cases listed
above, so let this serve as a warning that you should not use the @SneakyThrows mechanism without some deliberation!
You can pass any number of exceptions to the @SneakyThrows annotation. If you pass no exceptions, you may throw any
exception sneakily.
Because @SneakyThrows is an implementation detail and not part of your method signature, it is an error if you try to
declare a checked exception as sneakily thrown when you don't call any methods that throw this exception. (Doing so is perfectly legal
for throws statements to accomodate subclasses). Similarly, @SneakyThrows does not inherit.
For the nay-sayers in the crowd: Out of the box, Eclipse will offer a 'quick-fix' for uncaught exceptions that wraps the offending
statement in a try/catch block with just e.printStackTrace() in the catch block. This is so spectacularly non-productive
compared to just sneakily throwing the exception onwards, that Roel and Reinier feel more than justified in claiming that the
checked exception system is far from perfect, and thus an opt-out mechanism is warranted.
Currently usage of @SneakyThrows requires you to have lombok.jar in the classpath at runtime. However, in the future
we will attempt to eliminate this requirement - when we figure out how we can do that. If anyone has a good idea on how to make that happen, let us know!