java - Discover available port for derby

Question

This question is almost similar to this previous question Sockets: Discover port availability using Java. But somehow its not working properly when I check the derby listening port.

public static boolean isPortavailable(int port){
    ServerSocket ss = null;
    DatagramSocket ds = null;
    try{
        ss = new ServerSocket(port);
        ss.setReuseAddress(true);
        ds = new DatagramSocket(port);
        ds.setReuseAddress(true);
        return true;
    }
    catch(IOException e){
    }
    finally{
        if(ss != null){
        try{
            ss.close();
            ds.close();
        }
        catch(IOException e){
            /* should not be thrown */
        }
        }
    }
    return false;
}

Here is my main method

public static void main(String[] args){
    System.out.println("Derby:"+isPortAvailable(1527));
    System.out.println("Jetty:"+isPortAvailable(7080));
    System.out.println("Tomcat:"+isPortAvailable(8084));
}

I started services with the port for derby 1527, jetty 7080 and tomcat 8084. when I run this main method it gives the following result

Derby:true
Jetty:false
Tomcat:false

I am unable to find why Its giving wrong answer for derby, can anyone help. Thanks