#39 ✓invalid
Erwan Loisant

Cache.get() and the usage of generics

Reported by Erwan Loisant | October 5th, 2010 @ 11:56 AM

I'm wondering what the param clazz is needed for in the following method, found in the Cache class.

/**
 * Convenient clazz to get a value a class type;
 * @param <T> The needed type
 * @param key The element key
 * @param clazz The type class
 * @return The element value or null
 */
@SuppressWarnings("unchecked")
public static <T> T get(String key, Class<T> clazz) {
    return (T) cacheImpl.get(key);
}

AFAIK clazz isn't doing anything here. The return type is derived from the type of the variable in the calling context, as in:

Foo foo = cache.get("key")

The first would set the type of T to Foo. Then we happen to require a second param containing a Class instance of type Class, but I don't think that is needed at all for the requested functionality (to return the cached object with the correct type and avoid casting).

Imported from Launchpad: https://bugs.launchpad.net/play/+bug/632753

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