I have a class that is trying to read packet from other Xbees connected with Arduino board. Here is the class:
public class XbeeReceiver2 {
private XBee xbee;
private int[] payloadToSend;
private int[] payloadReceived;
private Queue<XBeeResponse> queue = new ConcurrentLinkedQueue<XBeeResponse>();
public XBeeResponse response;
private final static Logger LOGGER = Logger.getLogger(XbeeReceiver2.class .getName());
public XbeeReceiver2(){
xbee = new XBee();
}
public void openXbeeConnection(String portNumber){
try {
xbee.open(portNumber, 9600);
xbee.addPacketListener(new PacketHandler());
} catch (XBeeException e) {
System.out.println("" + portNumber + " - connection problems");
e.printStackTrace();
}
};
public void readPacket(){
System.out.println(queue.isEmpty());
while((response = queue.poll()) != null){
try {
response = xbee.getResponse();
LOGGER.info("received response " + response.toString());
if (response.getApiId() == ApiId.ZNET_RX_RESPONSE){
ZNetRxResponse rx = (ZNetRxResponse) response;
payloadReceived = rx.getData();
}
} catch (XBeeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
public void closeXbeeConnection(){
xbee.close();
};
private class PacketHandler implements PacketListener{
@Override
public void processResponse(XBeeResponse response) {
//if (response instanceof XBeeResponse){
queue.offer(response);
//}
}
}
}
In the main program, I have the following piece of code:
XbeeReceiver2 xbeeReceiver = new XbeeReceiver2();
xbeeReceiver.openXbeeConnection("COM23");
xbeeReceiver.readPacket();
When I run it, however, the readPacket() method will get stuck at the beginning of the loop, since there is any instance of XbeeResponse stored in the queue. However, when I change the while condition in readPacket() method from while((response = queue.poll()) != null) to while(true), then it works. This means I am getting the response, but I do not think that using while(true) is the good solution as I read on some pages. Therefore I prefer to work with PacketListener.
If anyone has an idea, why my PacketListener does not work, would be great.
Ok I have found a solution, it was not that hard. Before starting the loop, I got a response from Xbee and added it into queue, so it did not break at the beginning. The same I did at the end of while loop, where I added another response.
This is my openConnection method:
public void openXbeeConnection(String portNumber){
try {
xbee.open(portNumber, 57600);
xbee.addPacketListener(new PacketHandler());
response = xbee.getResponse();
queue.add(response);
} catch (XBeeException e) {
System.out.println("" + portNumber + " - connection problems");
e.printStackTrace();
}
};
And in the while loop of the main method it looks like this:
while ((response = queue.poll()) != null){
//LOGGER.info(response.toString());
int[] payload = xbeeReceiver.readPacket();
dbHandler.updateDB(payload);
int[] payloadToSend2 = dbHandler.retrieveDataFromFB();
xbeeReceiver.sendPacket(payloadToSend2);
try {
XBee xbee = xbeeReceiver.getXbee();
response = xbee.getResponse();
queue.add(response);
} catch (XBeeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}