This document discusses the basics of J2ME Record Management System (RMS) which allows MIDlets to persistently store and retrieve data even after a device is switched off. It stores data in binary format records within a record store on the mobile device. The key classes for managing records are RecordStore, RecordEnumeration, RecordComparator, RecordFilter and RecordListener in the javax.microedition.rms package. Methods like openRecordStore(), addRecord(), getRecord(), and deleteRecord() allow managing records by opening, inserting, retrieving and deleting them from a record store.

1. J2ME –
Record management system
Rohan Chandane
rohan.chandane@indiatimes.com
This notes are created by me, Rohan Chandane as learning material while pursuing MSc (CA) from SICSR. (CC) 2005-07

2. Basics
 Record Management System (RMS)
 Provides a mechanism
 MIDlets can
 Persistently store data
 Retrieve it later even if device switched off
 It stores data in binary format in mobile
device

3. Overview of J2ME RMS and
MIDlet interfacing

4. Records and Record Store
 Storage Mechanism termed as
 Record Store
 Record Store consist
 Records – Individual units of storage
 Record
 Is an array of bytes
 Stored in binary file

5. Package
 Package used
 javax.microedition.rms
 For Record stored class used
 javax.microedition.rms.RecordStore
 Provides several methods to manage
records in Record Store
 Insert
 Update
 Delete

6. RecordStore Class
 Methods in RecordStore
 openRecordStore()
 Open Record Store
 closeRecordStore()
 Close Record Store
 deleteRecordStore()
 Delete Record Store
 enumerateRecords()
 Used to obtain enumeration object, which
represents entire set of records in Record Store

7. Continued…
 getName()
 Used to obtain name of Record Store
 getRecord()
 Retrieve a record from Record set
 getNumRecord()
 Obtain a number of records in Record Store
 addRecord()
 Add record to Record Store
 deleteRecord()
 Delete record from Record Store

8. Continued…
 Interfaces in RMS package
 RecordEnumeration
 Provide navigation in both direction through
record store
 It has following methods defined
 nextRecordId() – returns Id of next record
 nextRecord() – returns next record
 previousRecordId() – returns Id of previous record
 previousRecord() – returns previous record
 hasNextElement() – true, if there is next record
 hasPreviousElement() – true, if there is previous
record

9. Continued…
 RecordComparator
 Provide comparison between two records in a
record store
 RecordFilter
 Provide a mechanism to check if a record
matches a specific criterion
 RecordListener
 Provide an event listener that is notified when
event is added, deleted or modified

10. Managing record stores
 Open a RecordStore
RecordStore rs = RecordStore.openRecordStore(quot;MyAppointmentsquot;,true);
 Close a RecordStore
Rs.closeRecordStore();
 Delete a RecordStore
RecordStore.deleteRecordStore(quot;MyAppointmentsquot;);

11. Continued…
 Insert a record
String appt = quot;new recordquot;;
byte bytes[] = appt.getBytes();
rs.addRecord(bytes,0,bytes.length);
 Updating records
String newappt = quot;update recordquot;;
Byte data = newappt.getBytes();
Rs.setRecord(1, data, 0, data.length());

12. Continued…
 Deleting records
Rs.deleteRecord(1);