Re: Casting an object to a genericized TreeMap
On May 3, 6:41 am, "Kaiser S." <sau...@name.invalid> wrote:
Ingo R. Homann a =E9crit :
Hi,
Kaiser S. wrote:
What do you think of this code ? Is there a better way do enforce this
kind of cast ?
public static <K, V> TreeMap<K, V> treemap(Object o, Class<K>
keyClass, Class<V> valueClass) {
TreeMap<?, ?> tm = (TreeMap)o; // warning 1
for (Map.Entry<?, ?> couple : tm.entrySet()) {
keyClass.cast(couple.getKey());
valueClass.cast(couple.getValue());
}
return (TreeMap)o; // warning 2
}
called with:
TreeMap<String, Double> tm = treemap(o, String.class, Double.class);
You know that your code does not do anything, and that the following
would do exactly the same?
public static <K, V> TreeMap<K, V> treemap(Object o) {
return (TreeMap<K,V>)o; // warning
}
Well i hope not. I check the class of all the keys and values; you must
have seen it...
Now the doc of Class.cast says it throw a ClassCastException if the cast
is invalid, so after the for loop, i can make the ugly cast because i'm
sure i won't get a ClassCastException somewhere else in my program.
If you really want to check the types, I suggest using instanceof
I'm kind of curious why you go through the effort. Whats going on that
you have a TreeMap object thats not in a TreeMap type reference?
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