The constructor in Connect is not being explicitly called by DataConnect, so it is being called by default (and no parameters are being passed to it. Connect's constructor though requires an integer (port) argument. To fix it add a line to the DataConnect constructor to properly call the Connect constructor.:
Change
public DataConnect(int port) {
PORTNUM = port;
}
to
Code:
public DataConnect(int port) {
	super(port);    
        PORTNUM = port;
}