Java simulation code

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Enumeration;
import java.io.OutputStream;
import gnu.io.*;

public class SerialGenerator {

	private static final String PORT_NAME = "COM3";
	static SerialPort serialPort;
	private static BufferedReader input = null;
	private static OutputStream output = null;
	private static CommPortIdentifier portId;
	private static final String PORT_NAMES[] = {
			"/dev/tty.usbserial-A9007UX1", // Mac OS X
                        "/dev/ttyACM0", // Raspberry Pi
			"/dev/ttyUSB0", // Linux
			"COM3", // Windows
	};
	private static final int TIME_OUT = 2000;
	/** Default bits per second for COM port. */
	private static final int DATA_RATE = 9600;


	public static void main(String[] args) throws IOException, UnsupportedCommOperationException, InterruptedException {

		setUpPort();
		System.out.print("Enter goal speed:\t");
		float goalSpeed = getInput();
		System.out.print("Enter current speed:\t");
		float currentSpeed = getInput();
		simulation( goalSpeed, currentSpeed );

	}

	private static float getInput() throws IOException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

		return new Float(reader.readLine());
	}

	private static void setUpPort() throws IOException, UnsupportedCommOperationException {

		Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

		//First, Find an instance of serial port as set in PORT_NAMES.
		while (portEnum.hasMoreElements()) {
			CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
			for (String portName : PORT_NAMES) {
				if (currPortId.getName().equals(portName)) {
					portId = currPortId;
					break;
				}
			}
		}
		try {
			serialPort = (SerialPort) portId.open(PORT_NAME, TIME_OUT);
		} catch (PortInUseException e) {
			System.err.println("Port not connected!");
			e.printStackTrace();
		}
		serialPort.setSerialPortParams(DATA_RATE, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
		input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
		output = serialPort.getOutputStream();

	}

	private static void simulation( float goalSpeed, float currentSpeed ) throws IOException, InterruptedException {

		while( true ) {
			if ( currentSpeed > 18 ) {
				goalSpeed = 1;
			}
			String outputString = goalSpeed + "," + currentSpeed;
			System.out.println("Sending: " + outputString);
			System.out.println();
			output.write(outputString.getBytes());
			System.out.println("Return Value: ");
			try {
				String inputRet = input.readLine();
				System.out.println(inputRet);
			} catch ( NullPointerException e ) {
				System.out.println("No return value!" );
			} catch ( IOException e ) {
				System.out.println("No return value!" );
			}

			finally {
				currentSpeed += 1;
				Thread.sleep(1500);
			}

		}
	}

}