AS Java supports server cache for static resources and dynamic resources identified to be cached by the application. An application can define that a resource is to be cached by setting the appropriate ICM cache headers. Caching is done (files and responses are stored) in ICM, so AS Java caching benefits from all features of ICM caching.
Once a response is cached, the cached value is not updated if the original static file is changed.
In this case, you have to do some manual work to ensure that the cache does not contain irrelevant content when a resource changes. You must clear the content of the HTTP cache, by using the ICM administration console, or using CLEAR_HTTP_CACHE shell command, or using SAP NetWeaver Administrator. It guarantees that the next time a user requests the updated resource, the newest version of it is stored into the cache.