Java for loop doesnt execute - for-loop

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

In this line
//Its not executing this....
for(int i=0; i > ((List) btDevice).size(); i++) {
You have turned the > the wrong way... try
for(int i=0; i < ((List) btDevice).size(); i++) {
instead.
(The reason it doesn't iterate, is because the initial value, 0, is not greater than the size of the list!)
In your first loop:
//Its not executing this...
for(int i=0; i< devicesDiscovered.size(); i++) {
System.out.println("test if this gets output");
it must be the case that devicesDiscovered is empty. I suggest you do
System.out.println(devicesDiscovered.size());
before the loop to debug.

Answer 2

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.