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  1. #1
    Regular Contributor
    Join Date
    Aug 2009
    Location
    Iran - Tabriz
    Posts
    111

    probleam with getDiscoveryAgent()

    Hi
    i want to use mobile device bluetooth , i use this code but there is probleam with this method getDiscoveryAgent() . this error shown :
    Null pointer java/lang/nullpointer exeption
    this is my code :
    Code:
    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    
    import java.util.Vector;
    import java.io.*;
    import javax.bluetooth.*;
    import javax.microedition.lcdui.*;
    import javax.microedition.midlet.*;
    
    /**
     * @author mahdi
     */
    public class Midlet extends MIDlet implements CommandListener {
    
        LocalDevice local = null;
        DiscoveryAgent agent = null;
        List activeDevices = new List("Active Devices", List.IMPLICIT);
        Display display;
    
        public void startApp() {
            display = Display.getDisplay(this);
            doDeviceDiscovery();
            display.setCurrent(activeDevices);
        }
    
        public void pauseApp() {
        }
    
        public void destroyApp(boolean unconditional) {
        }
    
        public void commandAction(Command c, Displayable d) {
        }
    
        public void doDeviceDiscovery() {
            try {
                local = LocalDevice.getLocalDevice();
            } catch (BluetoothStateException ex) {
                ex.printStackTrace();
            }
            agent = local.getDiscoveryAgent();
        }
    }
    and this is out put on netbeans :
    Smart card communication error 0x80100017
    The specified reader is not currently available for use
    Using Untrusted simulated domain
    "Series 40 5th Edition SDK, Feature Pack 1" Instance #6500500 Ready for Future Connections
    "Series 40 5th Edition SDK, Feature Pack 1" Connection Terminated
    can any body help me ?
    thanks

  2. #2
    Registered User
    Join Date
    Sep 2007
    Location
    Bangalore
    Posts
    868

    Re: probleam with getDiscoveryAgent()

    Hi mahdi68,

    Null pointer exception is coming bcoz in the doDeviceDiscovery() method when you call LocalDevice.getLocalDevice(); you got the exception it is caught in the catch block and the next statement is operatening on the local varibale which is not initilized .

    For more in formation on the bluetooth example please refer the forum nokia wiki
    http://wiki.forum.nokia.com/index.ph...hat_HelloWorld
    http://wiki.forum.nokia.com/index.ph...r_more_devices

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