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

Take this one, it's much faster than creating a new HashMap, if it's already one, but still secure, as each element is checked against it's type...

@SuppressWarnings("unchecked")
public static  HashMap toHashMap(Object input, Class key, Class value) {
       assert input instanceof Map : input;

       for (Map.Entry e : ((HashMap) input).entrySet()) {
           assert key.isAssignableFrom(e.getKey().getClass()) : "Map contains invalid keys";
           assert value.isAssignableFrom(e.getValue().getClass()) : "Map contains invalid values";
       }

       if (input instanceof HashMap)
           return (HashMap) input;
       return new HashMap((Map) input);
    }