import javax.comm.*;


public class PortWatcher implements CommPortOwnershipListener {

  String portName;

  public PortWatcher(String portName) throws NoSuchPortException {
    this.portName = portName;
    CommPortIdentifier portIdentifier = 
     CommPortIdentifier.getPortIdentifier(portName);
    portIdentifier.addPortOwnershipListener(this);
  }
  
  public void ownershipChange(int type) {
  
    switch (type) {
    
      case CommPortOwnershipListener.PORT_OWNED:
        System.out.println(portName + " has become unavailable");
        break;
      case CommPortOwnershipListener.PORT_UNOWNED:
        System.out.println(portName + " has become available");
        break;
      case CommPortOwnershipListener.PORT_OWNERSHIP_REQUESTED:
        System.out.println("An application has requested onwership of " 
         + portName);
        break;
      default: 
        System.out.println("Unknown port ownership event, type " + type);
    }
  
  }

  public static void main(String[] args) {
    
    try {
      PortWatcher pw = new PortWatcher(args[0]);
    }
    catch (Exception e) {
      System.err.println("Usage: java PortWatcher port_name");
    }
  
  }

}