Java Magazine - July/August 2012

new Thread() {
public void run() {
try {
// the address book; it's easy to add other lists
ContactList addressbook =
(ContactList)( PIM.getInstance().openPIMList(
} catch (Exception ex) {
ex.printStackTrace();
}
}
}.start();

COMMUNITY JAVA IN ACTION

Figure 3

Figure 4

createBackup(), although the latter is private and called only via the startBackup() method.

The startBackup() method is called either automatically when the MIDlet starts (via your initiation or via the PushRegistry alarm) or when you select the Do Backup Now UI option.

As expected, the startBackup() method first checks to see whether a backup destination has been defined. If the destination has not been defined, it alerts you that the backup can’t start. Next, it creates a thread to do the backup in a manner that will not block the main thread. See Listing 6.

In the code in Listing 6, I have backed up only the address book. It would be easy to add a to-do list, a calendar list, or any other data that the MIDlet may

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compresses it as it goes along. The actual looking up of the data is done in the createBackup() method.

The code in Listing 7 goes through the items in the address book, looks up a valid data_format for serializing the items (provided via the PIM API) and iterates over individual items, while adding these items to the compression stream. At the end, the stream is flushed and the data written out.

Once the createBackup() method is finished, the startBackup() method uses the doSend() method of the BluetoothServices class we discussed earlier to actually send the data to the connected device.

If you have established a trusted and
paired connection between your device
and its backup destination, you will get
the data in a pre-established Bluetooth
Exchange folder. I have tested this pro-
cess with a live device (Nokia N95) and
confirmed that it works perfectly. See
Figure 3, Figure 4, and Figure 5, which
show the activation of the PushRegistry,
the destination confirmation, and data
transfer confirmation on the target
device. </article>

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Figure 5

access (which, admittedly, is limited and heavily implementation dependent).

To make the data transfer faster, I used an external library to compress the data before it is sent over the Bluetooth channel. This library, called compress- j2me, is extremely small and provides good compression.

I start by creating two output streams: one for holding the data and the other to compress it. The compression stream takes the first stream as the input and