January 2002
Intermediate to advanced
264 pages
8h 3m
English
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Chapter 8. Database Programming
A database is a non-volatile place for storing the state of objects. For some applications, you might need objects to exist even after the application that created them closes. Without a storage mechanism, objects and their states are destroyed when an application closes. However, if you save objects to a persistent storage facility, such as a database, they can be read in later by the same application or even other applications.
The persistent storage facilities provided in the J2SE platform, such as the JDBC and Object Serialization APIs, are too large for handheld devices with a small memory footprint. Storage requirements vary significantly from one resource-constrained device to another. J2ME and the MIDP solve this problem by using the Record Management System (RMS).
This chapter introduces the details of the MIDP RMS, a persistent storage facility for MIDlets, and shows you how to develop MIDP database applications, using an example involving stocks. Throughout this chapter, the terms record store and database are used interchangeably.
The Record Management System
An RMS database (or record store) consists of a collection of records
that remain persistent after the MIDlet closes. When you invoke the
MIDlet again, it can retrieve data from the persistent record store.
However, to use the RMS, we need to get familiar with some of the
classes and concepts provided by the
javax.microedition.rms
package.
Record Stores
Record stores, which are ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.