Java Magazine - July/August 2012

//mobile and embedded /

Wirelessly Back Up Your
Device’s Address Book
Learn to create a MIDlet to schedule a backup of your address book—and more.
VIKRAM GOYAL

JAVA IN ACTION

Java ME applications are notori- ously hard to back up. In this
article, I will go through the pro-
cess of creating a MIDlet applica-
tion that will allow you to select a
destination within your Bluetooth
network, create a schedule to back
up your address book, perform an
on-demand backup, and log (and
view) all of this activity. You can,
in addition, use this MIDlet to
extend backup activities to cover
other data that your device allows
you to access.

The Application Flow Figure 1 shows the target application in action.

The application flow is divided among the four options, which represent logical activities. You can look for destinations within the device’s Bluetooth environment, create and edit a schedule to control when the backup should be run automatically, perform an on-demand backup, and view the log.

Under normal circumstances,
you would create a schedule, set
up the destination once, and then
not worry about anything else. In
reality, only a signed application
with the proper permissions would
be able to do these things, because
you would need to grant the appli-
cation permission to read data and
initiate transfers (both
on the device and on
the target platform).

The basic code from that previous article hasn’t changed much because the process of sending the data is pretty much the same.

What is different is
that we need to search
for a Bluetooth con-
nection point, find the
To do so, we create a RecordStore
and hold this connection point
(the actual connection URL) in
that database. This RecordStore
is called the Backup Store in the
code in Listing 1, and it is initiated
when the MIDlet starts.

If this destination is not set, any attempt to create a backup will result in a simple message stating that a backup destination is not set.

The actual backup destination is set after the discovery of

You can, in
addition, use this
MIDlet to extend
backup activities to
cover other data that
your device allows
you to access.
Looking for
Destinations

I initiated the development of this MIDlet with the intention of using Wi-Fi to detect devices. However, even though the File Transfer API (JSR 75) supports the discoverability and manipulation of folders on remote devices, none of the implementation APIs (including Oracle’s) supports this. I used Bluetooth instead to discover devices and the services they allowed.

I described the Bluetooth discovery process and how we can use it to send files over the network in a previous article, but I will cover the main points again here.