The class description of AsynchronousDatagramChannel says "Asynchronous datagram channels allow more than one read/receive and write/send to be outstanding at any given time. ".
This statement contradicts the AsynchronousDatagramChannel.read() method specification which says "If a thread initiates a read operation before a previous read operation has completed then a ReadPendingException will be thrown. " and AsynchronousDatagramChannel.write() method spec which says "If a thread initiates a write operation before a previous write operation has completed then a WritePendingException will be thrown."