How do I address unchecked cast warnings?

Question

Eclipse is giving me a warning of the following form:

Type safety: Unchecked cast from Object to HashMap

This is from a call to

Answer 1

This stuff is hard, but here are my current thoughts:

If your API returns Object, then there's nothing you can do -- no matter what, you will be blindly casting the object. You let Java throw ClassCastExceptions, or you can check each element yourself and throw Assertions or IllegalArgumentExceptions or some such, but these runtime checks are all equivalent. You have to suppress the compile time unchecked cast no matter what you do at runtime.

I'd just prefer to blind cast and let the JVM perform its runtime check for me since we "know" what the API should return, and are usually willing to assume that the API works. Use generics everywhere above the cast, if you need them. You aren't really buying anything there since you still have the single blind cast, but at least you can use generics from there on up so the JVM can help you avoid blind casts in other pieces of your code.

In this particular case, presumably you can see the call to SetAttribute and see the type is going in, so just blind-casting the type to same on the way out is not immoral. Add a comment referencing the SetAttribute and be done with it.