Mega Code Archive
Read and write to the record store
<![CDATA[
/*--------------------------------------------------
* ReadWrite.java
*
* Read and write to the record store.
*
* No GUI interface, all output is to the console
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import javax.microedition.rms.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
public class ReadWrite extends MIDlet
{
private RecordStore rs = null;
static final String REC_STORE = "db_1";
public ReadWrite()
{
openRecStore(); // Create the record store
// Write a few records and read them back
writeRecord("J2ME and MIDP");
writeRecord("Wireless Technology");
readRecords();
closeRecStore(); // Close record store
deleteRecStore(); // Remove the record store
}
public void destroyApp( boolean unconditional )
{
}
public void startApp()
{
// There is no user interface, go ahead and shutdown
destroyApp(false);
notifyDestroyed();
}
public void pauseApp()
{
}
public void openRecStore()
{
try
{
// The second parameter indicates that the record store
// should be created if it does not exist
rs = RecordStore.openRecordStore(REC_STORE, true );
}
catch (Exception e)
{
db(e.toString());
}
}
public void closeRecStore()
{
try
{
rs.closeRecordStore();
}
catch (Exception e)
{
db(e.toString());
}
}
public void deleteRecStore()
{
if (RecordStore.listRecordStores() != null)
{
try
{
RecordStore.deleteRecordStore(REC_STORE);
}
catch (Exception e)
{
db(e.toString());
}
}
}
public void writeRecord(String str)
{
byte[] rec = str.getBytes();
try
{
rs.addRecord(rec, 0, rec.length);
}
catch (Exception e)
{
db(e.toString());
}
}
public void readRecords()
{
try
{
// Intentionally make this too small to test code below
byte[] recData = new byte[5];
int len;
for (int i = 1; i <= rs.getNumRecords(); i++)
{
if (rs.getRecordSize(i) > recData.length)
recData = new byte[rs.getRecordSize(i)];
len = rs.getRecord(i, recData, 0);
System.out.println("Record #" + i + ": " + new String(recData, 0, len));
System.out.println("------------------------------");
}
}
catch (Exception e)
{
db(e.toString());
}
}
/*--------------------------------------------------
* Simple message to console for debug/errors
* When used with Exceptions we should handle the
* error in a more appropriate manner.
*-------------------------------------------------*/
private void db(String str)
{
System.err.println("Msg: " + str);
}
}
]]>