How to cache null values with Ehcache 3

Question

I need to cache null values with Ehcache 3. For Ehcache 2 I found examples like here:

• http://www.ehcache.org/documentation/2.8/recipes/cachenull.html

// cache an explicit null value:
cache.put(new Element("key", null));

Element element = cache.get("key");

if (element == null) {

// nothing in the cache for "key" (or expired) ...
} else {

// there is a valid element in the cache, however getObjectValue() may be null:

Object value = element.getObjectValue();

if (value == null) {

    // a null value is in the cache ...

} else {

    // a non-null value is in the cache ...

• https://codereview.stackexchange.com/questions/60393/using-ehcache-the-right-way

Are there examples for this for Ehcache 3 as it seems net.sf.ehcache.Element doesn't exist anymore?

I have also seen this comment: https://github.com/ehcache/ehcache3/issues/1607

Indeed, you cannot cache a null value, this is also the behaviour of the JCache specification. If you need this in your application, either create a sentinel value or wrap your values from your application.

Of course I could build some logic if my return object is null put it to an other Set were I store only my keys for null elements. Of course also for reading I need to check my ehcache and my "special" Set.

Answer 1

Your question contains the answer, you need either to use the null object pattern or a related solution to wrap / hide your nulls.

There is no, and there will not be, support for null key or values in Ehcache 3.