source: liacs/se/RouteGUI/src/routegui/GPRMC.java@ 2

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package routegui;

import java.io.IOException;
import java.util.Calendar;
import org.jdesktop.swingx.mapviewer.GeoPosition;

/**
 *
 * @author rick
 * http://www.codepedia.com/1/The+GPRMC+Sentence
 */
public class GPRMC {
    /* 0: The Command Word */
    /**
     * 1: Satellite-Derived Time in UTC, in a compressed form "HHMMSS.XXX,"
     * 9: UTC Date, to be put into calendar format DDMMYY 
     */
    public Calendar calendar;
    /** 
     * 2: Satelite fix status 
     */
    public Boolean sateliteFixStatus;
    /** 
     * 3: latitudeDecimalDegrees HHMM.M
     * 4: latitudeHemisphere [N|S]
     * 5: DoubleitudeDecimalDegrees HHHMM.M
     * 6: DoubleitudeHemisphere [E|W]
     * converted to Geoposition
     */
    public GeoPosition position; 
    /**
     * 7: speed in knobs 
     */
    public Double speed; 
    /**
     * 8: bearing, measured as an "azimuth.", where 0 represents north, 
     * 90 represents east, 180 represents south and 270 represents west.
     */
    public Double bearing;
    /* 10: Empty */
    /* 11: Empty */
    /* 12: Empty */
    /* 13: Checksum field */

    private String getChecksum(String strLine) {
        int checksum = strLine.charAt(1);
        for (int i = 2; i < strLine.length() - 3; i++ ){
            checksum = checksum ^ strLine.charAt(i);            
        }
        return String.format("%1x", checksum);
    }
    
    GPRMC() {
        
    }
    
    
    GPRMC(String strLine)  {
        boolean result = process(strLine);
    }
            
    public boolean process(String strLine) {
        String[] strSub = strLine.split("[,*]");
        
        /* Checking sentence is valid using checksum */
        if (! getChecksum(strLine).equals(strSub[13])) {
            return false;
        }

        
        /* Set calendar */
        calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH, 
                Integer.parseInt(strSub[9].substring(0,2)));
        calendar.set(Calendar.MONTH, 
                Integer.parseInt(strSub[9].substring(2,4)));
        calendar.set(Calendar.YEAR, 
                Integer.parseInt(strSub[9].substring(4,6)) + 2000);
        calendar.set(Calendar.HOUR, 
                Integer.parseInt(strSub[1].substring(0,2)));
        calendar.set(Calendar.MINUTE, 
                Integer.parseInt(strSub[1].substring(2,4)));
        calendar.set(Calendar.SECOND, 
                Integer.parseInt(strSub[1].substring(4,6)));
            calendar.set(Calendar.MILLISECOND, 
                Integer.parseInt(strSub[1].substring(7,9)));
        
        /* Set fix status */
        sateliteFixStatus = strSub[2].equalsIgnoreCase("A");       
      
        if (sateliteFixStatus) {
            /** 
             * Set position, 
             * see: http://en.wikipedia.org/wiki/Geographic_coordinate_conversion
             * @todo: Milliseconds are ignored in calculation 
             */
            
            Double latitude = Double.parseDouble(strSub[3].substring(0, 2));
            latitude += Double.parseDouble(strSub[3].substring(2)) / 60;
            if (strSub[4].equalsIgnoreCase("S")) {
                latitude = latitude * -1;
            }

            Double longitude = Double.parseDouble(strSub[5].substring(0, 3));
            longitude += Double.parseDouble(strSub[5].substring(3)) / 60;
            if (strSub[6].equalsIgnoreCase("W")) {
                longitude = longitude * -1;
            }

            position = new GeoPosition(latitude, longitude);

            /* Set speed in knobs */
            speed = Double.parseDouble(strSub[7]);

            /* Set bearing if available */
            if (strSub[8].isEmpty()) {
                bearing = null;
            } else {
                bearing = Double.parseDouble(strSub[8]);
            }
        } 
    return true;
    }
}