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Changing Bluetooth discoverability in Java ME

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Revision as of 17:12, 24 March 2009


Article Metadata
Tested with
Devices(s): Nokia N78, Nokia 5800 XM, Nokia 6131
Keywords: javax.bluetooth.BluetoothStateException, javax.bluetooth.DiscoveryAgent, javax.bluetooth.LocalDevice
Created: (31 Jan 2009)
Last edited: copyeditor (24 Mar 2009)


The following code snippet demonstrates how to change discoverability using the Bluetooth API.

Discoverability mode can be set using the LocalDevice.setDiscoverable method. This method takes discoverability Id as a parameter. This parameter must have one of the following values:


More information on discoverability modes can be found in the JSR-82 specification.

Source file: BtDiscoverabilityMode.java

* Allows to select discover mode from Bluetooth device.

private List listModes;
* Discoverability mode id array.

private int[] modeArray;
* Instantiates a listModes.

private void setupModeList() {
listModes = new List( "Mode list", Choice.IMPLICIT );
listModes.setSelectCommand( CHANGE_COMMAND );
listModes.addCommand( BACK_COMMAND );
listModes.setCommandListener( this );
// adding discoverability modes to the list
listModes.append( "GIAC", null );
listModes.append( "LIAC", null );
listModes.append( "NOT DISCOVERABLE", null );
//setting mode id array values
modeArray[0] = DiscoveryAgent.GIAC;
modeArray[1] = DiscoveryAgent.LIAC;
modeArray[2] = DiscoveryAgent.NOT_DISCOVERABLE;
* From CommandListener.
* Called by the system to indicate that a command has been invoked on a
* particular displayable.
* @param command the command that was invoked
* @param displayable the displayable where the command was invoked

public void commandAction(Command command, Displayable displayable) {
if (command == EXIT_COMMAND) {
// Exit the MIDlet
} else if (command == EXECUTE_COMMAND) {
// Open discoverability mode list
display.setCurrent( listModes );
} else if ( command == CHANGE_COMMAND ) {
//get currently selected contact
int i = listModes.getSelectedIndex();
String item = listModes.getString( i );
printString( "Selected mode: " + item );
// Bringing back main form to the foreground
display.setCurrent( mainForm );
// Changing discoverability mode
changeMode( i );
} else if ( command == BACK_COMMAND ) {
display.setCurrent( mainForm );
* @param modeIndex

private void changeMode( int modeIndex ) {
LocalDevice devLocal = null;
try {
printString( "Getting local device ..." );
devLocal = LocalDevice.getLocalDevice();
} catch ( BluetoothStateException e ) {
printString( e.toString() );
try {
printString( "Changing discoverability mode" );
devLocal.setDiscoverable( modeArray[ modeIndex ] );
} catch ( BluetoothStateException e ) {
printString( e.toString() );
printString( "Discoverability mode changed." );


When the MIDlet is started, the main form with a text field will be displayed. To change the current bluetooth device mode, you should press the 'Modes' softkey, which displays a list of available modes.

When the list appears, select a specific mode and press the 'Change' softkey. The main form will be brought to the foreground. If the discoverability mode change procedure is successful, a 'Discoverability mode changed' message will appear.

Supplementary material

This code snippet is part of the stub concept, which means that it has been patched on top of a template application in order to be more useful for developers. The version of the Java ME stub application used as a template in this snippet is v1.1.

  • The patched, executable application that can be used to test the features described in this snippet is available for download at Media:BtDiscoverabilityMode.zip.
  • You can view all the changes that are required to implement the above-mentioned features. The changes are provided in unified diff and colour-coded diff (HTML) formats in Media:BtDiscoverabilityMode.diff.zip.
  • For general information on applying the patch, see Using Diffs.
  • For unpatched stub applications, see Example stub.
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