Question

I am having problems with my remote device discovery code for bluetooth scanning.
It scans, and prints the MAC addresses if i uncomment the “system.out.print(devicesDiscovered);

But i want to be able to extract each MAC address from the Vector and place it in a String.

I have two differant FOR loops to do this, but neither of them seem to be executing.

Code:

import java.io.IOException;
import java.util.List;
import java.util.Vector;
import javax.bluetooth.*;

public class BluetoothDeviceDiscovery {

    public static final Vector/*<RemoteDevice>*/ devicesDiscovered = new Vector();

    public static void main() throws IOException, InterruptedException {

        final Object inquiryCompletedEvent = new Object();

        devicesDiscovered.clear();

        final DiscoveryListener listener = new DiscoveryListener() {

            public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {              
                devicesDiscovered.addElement(btDevice);

                //
                String testingAgain = devicesDiscovered.toString();
                System.out.println("What?? : " + testingAgain);

                /*
                * As far as i know, the following two FOR loops do the same thing
                * But both of them are not being executed...
                */

                //Its not executing this...
                for(int i=0; i< devicesDiscovered.size(); i++) {
                    System.out.println("test if this gets output");
                    String test = (String) devicesDiscovered.elementAt(i);
                    System.out.println("Test: " + test);
                }                
                //Its not executing this....
                for(int i=0; i> ((List) btDevice).size(); i++){
                    System.out.println("test if this gets output 1");
                    String testing = (String) devicesDiscovered.toString();
                    System.out.print("Test1: " + testing);
                }
                //Prints the MAC addresses [macaddress, macaddress, macaddress, etc]
               // System.out.println(devicesDiscovered);



                /*
                 * Now need to extract each macaddress from devicesDiscovered
                 * and convert from a Vector to a String
                 */
            }

            public void inquiryCompleted(int discType) {
                System.out.println("Device Inquiry completed!");
                synchronized(inquiryCompletedEvent){
                    inquiryCompletedEvent.notifyAll();
                }
            }

            public void serviceSearchCompleted(int transID, int respCode) {
            }

            public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
            }
        };

        synchronized(inquiryCompletedEvent) {
            boolean started = LocalDevice.getLocalDevice().getDiscoveryAgent().startInquiry(DiscoveryAgent.GIAC, listener);
            if (started) {
                System.out.println("wait for device inquiry to complete...");
                inquiryCompletedEvent.wait();
                System.out.println(devicesDiscovered.size() +  " device(s) found");
            }
        }

    }
}

Can anyone spot any reason(s) as to why these two for loops are not working?

Thanks a lot
– Ryan

Answer 1

The execution of your code in my machine is the following:

BlueCove version 2.1.0 on bluez

wait for device inquiry to complete…

What?? : […]

test if this gets output

Test: …

Device Inquiry completed!

1 device(s) found

BlueCove stack shutdown completed

With the following for loop:

for(int i=0; i< devicesDiscovered.size(); i++) 
{
    System.out.println("test if this gets output");
    String test = (String) devicesDiscovered.elementAt(i).toString();
    System.out.println("Test: " + test);
}

I’ve noticed that you were testing which one of the for loops was generating the output that you wanted. I can say that the above one works but the second generates an exception. You are trying to cast a RemoteDevice object to a List and iterate through it (for(int i=0; i < ((List) btDevice).size(); i++)). That’s the reason for not working and therefore the exception.