Java RXTX help!

Ok, i have my java rxtx program, and im having problems, i dont know what is wrong. i installed the RXTX stuff, and im getting errors.

package serial;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import java.io.InputStream;
import java.io.OutputStream;
import processing.app.Preferences;

public class Main {
    static InputStream input;
    static OutputStream output;

    public static void main(String[] args) throws Exception{
        Preferences.init();
        System.out.println("Using port: " + Preferences.get("serial.port"));
        CommPortIdentifier portId = CommPortIdentifier.getPortIdentifier(
                Preferences.get("serial.port"));

        SerialPort port = (SerialPort)portId.open("serial talk", 4000);
        input = port.getInputStream();
        output = port.getOutputStream();
        port.setSerialPortParams(Preferences.getInteger("serial.debug_rate"),
                SerialPort.DATABITS_8,
                SerialPort.STOPBITS_1,
                SerialPort.PARITY_NONE);
        while(true){
            while(input.available()>0) {
                System.out.print((char)(input.read()));
            }
        }
    }
}

preferences.init() comes in and error and this is the error code it gives me when i try to run the program.

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code
        at serial.Main.main(Main.java:13)
Java Result: 1

but, if i delete it, (the preferences.init()) this is the output i get is...

Using port: null
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version   = RXTX-2.1-7
Exception in thread "main" gnu.io.NoSuchPortException
        at gnu.io.CommPortIdentifier.getPortIdentifier(CommPortIdentifier.java:218)
        at serial.Main.main(Main.java:15)
Java Result: 1

It sounds like you're having similar problems to what others have had using the Preferences object in the Silveira Neto tutorial.

See http://silveiraneto.net/2009/03/01/arduino-and-java/#comment-4322 for one solution: removing the Preferences references completely.

I should be clearer:

The "Using port: null" indicates the problem: that Preferences.get("serial.port") is returning null - that is, you haven't set a preference for the serial port to use. When CommPortIdentifier.getPortIdentifier() is called with null as the port of interest, it gives you the NoSuchPortException.