Question

My java app has a cache, and I’d like to swap out the current cache implementation and replace it with the guava cache.

Unfortunately, my app’s cache usage doesn’t seem to match the way that guava’s caches seem to work. All I want is to be able to create an empty cache, read an item from the cache using a “get” method, and store an item in the cache with a “put” method. I do NOT want the “get” call to be trying to add an item to the cache.

It seems that the LoadingCache class has the get and put methods that I need. But I’m having trouble figuring out how to create the cache without providing a “load” function.

My first attempt was this:

LoadingCache<String, String> CACHE = CacheBuilder.newBuilder().build();

But that causes this compiler error: incompatible types; no instance(s) of type variable(s) K1,V1 exist so that Cache conforms to LoadingCache

Apparently I have to pass in a CacheLoader that has a “load” method.

(I guess I could create a CacheLoader that has a “load” method that just throws an Exception, but that seems kind of weird and inefficient. Is that the right thing to do?)

Answer 1

CacheBuilder.build() returns a non-loading cache. Just what you want. Just use

Cache<String, String> cache = CacheBuilder.newBuilder().build();