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if (names[i].equals(name))
return values[i];
}
return null; // not found
}
// ...
}
Class
IntegerLookup
is not itself a generic class, rather it implements a
generic interface, providing a concrete type
Integer
in place of the ab-
stract type parameter
T
. Compared to the
SimpleLookup
class, this class
can store items in an array of
Integer
and
find
returns an
Integer
.
How would we modify
processValues
to work with generic implementa-
tions of
Lookup
? Here's one attempt to do so:
void processValues(String[] names, Lookup<Object> table) {
for (int i = 0; i < names.length; i++) {
Object value = table.find(names[i]);
if (value != null)
processValue(names[i], value);
}
}
This compiles okay, and appears reasonable
table
is an instance of a
class that implements
Lookup
for any kind of
Object
. As
Integer
instances
are
Object
instances then we should be able to do this:
Lookup<Integer> l = new IntegerLookup();
// ... add entries to l ...
String[] names = { "One", "two" };
processValues(names, l); // INVALID: won't compile
