General practices - managing large amounts of data

Question

I have a basic question regarding data management in Java. Right now, I'm working on a program that deals with hundreds of "pages" of content, each with images, HTML, and some state data. I maintain info on each page in a ContentItem object. Similarly, there can be many categories of content, each of which I maintain in a ContentCategory object.
At this point, I am controlling access to data using manager classes. For example, I have a ContentManager class that contains a global, static list of content and has the methods you'd expect such a class to have (getContent, addContent, deleteContent, etc.). Similarly, I have a CategoryManager class.
Basically, any time my program has to deal with large amounts of data or objects, I sort of fall back on these manager classes. I'm wondering if this is a reasonable practice or not. If not, perhaps some of the more experienced developers here could recommend a design pattern that fits these situations.

Answer 1

Thanks for the reply. I do have a sort of ad-hoc database that I'm using. I have a class called ContentReference which holds just the basic state information about a ContentItem. The actual HTML and image data are stored on disk and retrieved as needed. The files for each content item are just serialized copies of ContentItem objects. Each content item has a unique ID value which is passed to the ContentManager's getContent method. The getContent method retrieves the object from disk and returns the ContentItem object. The filenames for all the content items are based on the ID value, so the getContent method doesn't have to search through all the files until it finds the right one.
In doing this, I don't have to keep all the HTML and image data in memory. Only the ContentReference objects are kept in memory. ContentItems are loaded as needed. It seems a little messy to have two objects that refer to the same thing, but I didn't see any other way of doing it.