How do you achieve caching in Java based application?

[Arun Singh Raaj]

When you develop a Java based web application, how do you achieve caching nowadays?
I've studied Caching in Hibernate, there were 1st level cache, 2nd level cache and Query level cache.  Is that all about caching?
I want to know about the real time applications, is Caching achieved by using third party software?
Is caching part separate from the application code, like a load balancer?
Or it is something that you create a separate class where you use Collection to save the data?

Thanks in advance.

[Tim Moores]

Caching can take many forms. You could create your own cache using data structures in your code (maybe using collections, maybe using other classes), or you could use a 3rd party library (like JBoss Cache or EhCache), or you could use an external caching server like Memcache or Redis.

[Arun Singh Raaj]

Thanks.
May I know which one is the most preferable way among you've given, to create cache nowadays?
And I want to know where does the cache reside, is it stored into the db?

[Tim Moores]

May I know which one is the most preferable way among you've given, to create cache nowadays?

That can't be answered in general, it depends on the circumstances.

And I want to know where does the cache reside, is it stored into the db?

In memory. In a way, caches ARE databases, but their contents are not persisted. If the applications powers down, whatever was in the cache is lost - so the app needs to take care of filling the cache at startup time, or during the lifetime of the app.

[Stephan van Hulst]

Remember, caching is one of the hardest issues in computer science.

The other three are naming things and off-by-one errors.

[Samuel Marchant]

Tim Moores wrote:

May I know which one is the most preferable way among you've given, to create cache nowadays?

That can't be answered in general, it depends on the circumstances.

And I want to know where does the cache reside, is it stored into the db?

In memory. In a way, caches ARE databases, but their contents are not persisted. If the applications powers down, whatever was in the cache is lost - so the app needs to take care of filling the cache at startup time, or during the lifetime of the app.

Of coincidence, this is basically a cache set up for J2EE server API that I wrote, most cache I've heard of are as being said here, not part of the server API

Ramfile API doc
https://www.scribd.com/document/472437350/javax-servlet-Ramfile-Javadoc

Source code to insert into server source
https://www.scribd.com/document/470554983/javax-servlet-Ramfile-Interface-and-org-apache-catalina-core-RAMfileArray

I'm discussing it in other threads