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

The obvious answer, of course, is not to do the unchecked cast.

If it's absolutely necessary, then at least try to limit the scope of the @SuppressWarnings annotation. According to its Javadocs, it can go on local variables; this way, it doesn't even affect the entire method.

Example:

@SuppressWarnings("unchecked")
Map myMap = (Map) deserializeMap();

There is no way to determine whether the Map really should have the generic parameters . You must know beforehand what the parameters should be (or you'll find out when you get a ClassCastException). This is why the code generates a warning, because the compiler can't possibly know whether is safe.