Java, convert lat/lon to UTM

I was able to use Geotools 2.4 to get something that works, based on some example code.

double utmZoneCenterLongitude = ...  // Center lon of zone, example: zone 10 = -123
int zoneNumber = ...                 // zone number, example: 10
double latitude, longitude = ...     // lat, lon in degrees

MathTransformFactory mtFactory = ReferencingFactoryFinder.getMathTransformFactory(null);
ReferencingFactoryContainer factories = new ReferencingFactoryContainer(null);

GeographicCRS geoCRS = org.geotools.referencing.crs.DefaultGeographicCRS.WGS84;
CartesianCS cartCS = org.geotools.referencing.cs.DefaultCartesianCS.GENERIC_2D;

ParameterValueGroup parameters = mtFactory.getDefaultParameters("Transverse_Mercator");
parameters.parameter("central_meridian").setValue(utmZoneCenterLongitude);
parameters.parameter("latitude_of_origin").setValue(0.0);
parameters.parameter("scale_factor").setValue(0.9996);
parameters.parameter("false_easting").setValue(500000.0);
parameters.parameter("false_northing").setValue(0.0);

Map properties = Collections.singletonMap("name", "WGS 84 / UTM Zone " + zoneNumber);
ProjectedCRS projCRS = factories.createProjectedCRS(properties, geoCRS, null, parameters, cartCS);

MathTransform transform = CRS.findMathTransform(geoCRS, projCRS);

double[] dest = new double[2];
transform.transform(new double[] {longitude, latitude}, 0, dest, 0, 1);

int easting = (int)Math.round(dest[0]);
int northing = (int)Math.round(dest[1]);

No Library, No Nothing. Copy This!

Using These Two Classes , You can Convert Degree(latitude/longitude) to UTM and Vice Versa!

private class Deg2UTM
{
    double Easting;
    double Northing;
    int Zone;
    char Letter;
    private  Deg2UTM(double Lat,double Lon)
    {
        Zone= (int) Math.floor(Lon/6+31);
        if (Lat<-72) 
            Letter='C';
        else if (Lat<-64) 
            Letter='D';
        else if (Lat<-56)
            Letter='E';
        else if (Lat<-48)
            Letter='F';
        else if (Lat<-40)
            Letter='G';
        else if (Lat<-32)
            Letter='H';
        else if (Lat<-24)
            Letter='J';
        else if (Lat<-16)
            Letter='K';
        else if (Lat<-8) 
            Letter='L';
        else if (Lat<0)
            Letter='M';
        else if (Lat<8)  
            Letter='N';
        else if (Lat<16) 
            Letter='P';
        else if (Lat<24) 
            Letter='Q';
        else if (Lat<32) 
            Letter='R';
        else if (Lat<40) 
            Letter='S';
        else if (Lat<48) 
            Letter='T';
        else if (Lat<56) 
            Letter='U';
        else if (Lat<64) 
            Letter='V';
        else if (Lat<72) 
            Letter='W';
        else
            Letter='X';
        Easting=0.5*Math.log((1+Math.cos(Lat*Math.PI/180)*Math.sin(Lon*Math.PI/180-(6*Zone-183)*Math.PI/180))/(1-Math.cos(Lat*Math.PI/180)*Math.sin(Lon*Math.PI/180-(6*Zone-183)*Math.PI/180)))*0.9996*6399593.62/Math.pow((1+Math.pow(0.0820944379, 2)*Math.pow(Math.cos(Lat*Math.PI/180), 2)), 0.5)*(1+ Math.pow(0.0820944379,2)/2*Math.pow((0.5*Math.log((1+Math.cos(Lat*Math.PI/180)*Math.sin(Lon*Math.PI/180-(6*Zone-183)*Math.PI/180))/(1-Math.cos(Lat*Math.PI/180)*Math.sin(Lon*Math.PI/180-(6*Zone-183)*Math.PI/180)))),2)*Math.pow(Math.cos(Lat*Math.PI/180),2)/3)+500000;
        Easting=Math.round(Easting*100)*0.01;
        Northing = (Math.atan(Math.tan(Lat*Math.PI/180)/Math.cos((Lon*Math.PI/180-(6*Zone -183)*Math.PI/180)))-Lat*Math.PI/180)*0.9996*6399593.625/Math.sqrt(1+0.006739496742*Math.pow(Math.cos(Lat*Math.PI/180),2))*(1+0.006739496742/2*Math.pow(0.5*Math.log((1+Math.cos(Lat*Math.PI/180)*Math.sin((Lon*Math.PI/180-(6*Zone -183)*Math.PI/180)))/(1-Math.cos(Lat*Math.PI/180)*Math.sin((Lon*Math.PI/180-(6*Zone -183)*Math.PI/180)))),2)*Math.pow(Math.cos(Lat*Math.PI/180),2))+0.9996*6399593.625*(Lat*Math.PI/180-0.005054622556*(Lat*Math.PI/180+Math.sin(2*Lat*Math.PI/180)/2)+4.258201531e-05*(3*(Lat*Math.PI/180+Math.sin(2*Lat*Math.PI/180)/2)+Math.sin(2*Lat*Math.PI/180)*Math.pow(Math.cos(Lat*Math.PI/180),2))/4-1.674057895e-07*(5*(3*(Lat*Math.PI/180+Math.sin(2*Lat*Math.PI/180)/2)+Math.sin(2*Lat*Math.PI/180)*Math.pow(Math.cos(Lat*Math.PI/180),2))/4+Math.sin(2*Lat*Math.PI/180)*Math.pow(Math.cos(Lat*Math.PI/180),2)*Math.pow(Math.cos(Lat*Math.PI/180),2))/3);
        if (Letter<'M')
            Northing = Northing + 10000000;
        Northing=Math.round(Northing*100)*0.01;
    }
}

private class UTM2Deg
{
    double latitude;
    double longitude;
    private  UTM2Deg(String UTM)
    {
        String[] parts=UTM.split(" ");
        int Zone=Integer.parseInt(parts[0]);
        char Letter=parts[1].toUpperCase(Locale.ENGLISH).charAt(0);
        double Easting=Double.parseDouble(parts[2]);
        double Northing=Double.parseDouble(parts[3]);           
        double Hem;
        if (Letter>'M')
            Hem='N';
        else
            Hem='S';            
        double north;
        if (Hem == 'S')
            north = Northing - 10000000;
        else
            north = Northing;
        latitude = (north/6366197.724/0.9996+(1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)-0.006739496742*Math.sin(north/6366197.724/0.9996)*Math.cos(north/6366197.724/0.9996)*(Math.atan(Math.cos(Math.atan(( Math.exp((Easting - 500000) / (0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting - 500000) / (0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3))-Math.exp(-(Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*( 1 -  0.006739496742*Math.pow((Easting - 500000) / (0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3)))/2/Math.cos((north-0.9996*6399593.625*(north/6366197.724/0.9996-0.006739496742*3/4*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.pow(0.006739496742*3/4,2)*5/3*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996 )/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4-Math.pow(0.006739496742*3/4,3)*35/27*(5*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/3))/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2))+north/6366197.724/0.9996)))*Math.tan((north-0.9996*6399593.625*(north/6366197.724/0.9996 - 0.006739496742*3/4*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.pow(0.006739496742*3/4,2)*5/3*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996 )*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4-Math.pow(0.006739496742*3/4,3)*35/27*(5*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/3))/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2))+north/6366197.724/0.9996))-north/6366197.724/0.9996)*3/2)*(Math.atan(Math.cos(Math.atan((Math.exp((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3))-Math.exp(-(Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3)))/2/Math.cos((north-0.9996*6399593.625*(north/6366197.724/0.9996-0.006739496742*3/4*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.pow(0.006739496742*3/4,2)*5/3*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4-Math.pow(0.006739496742*3/4,3)*35/27*(5*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/3))/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2))+north/6366197.724/0.9996)))*Math.tan((north-0.9996*6399593.625*(north/6366197.724/0.9996-0.006739496742*3/4*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.pow(0.006739496742*3/4,2)*5/3*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4-Math.pow(0.006739496742*3/4,3)*35/27*(5*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/3))/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2))+north/6366197.724/0.9996))-north/6366197.724/0.9996))*180/Math.PI;
        latitude=Math.round(latitude*10000000);
        latitude=latitude/10000000;
        longitude =Math.atan((Math.exp((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3))-Math.exp(-(Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2)/3)))/2/Math.cos((north-0.9996*6399593.625*( north/6366197.724/0.9996-0.006739496742*3/4*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.pow(0.006739496742*3/4,2)*5/3*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2* north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4-Math.pow(0.006739496742*3/4,3)*35/27*(5*(3*(north/6366197.724/0.9996+Math.sin(2*north/6366197.724/0.9996)/2)+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/4+Math.sin(2*north/6366197.724/0.9996)*Math.pow(Math.cos(north/6366197.724/0.9996),2)*Math.pow(Math.cos(north/6366197.724/0.9996),2))/3)) / (0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2))))*(1-0.006739496742*Math.pow((Easting-500000)/(0.9996*6399593.625/Math.sqrt((1+0.006739496742*Math.pow(Math.cos(north/6366197.724/0.9996),2)))),2)/2*Math.pow(Math.cos(north/6366197.724/0.9996),2))+north/6366197.724/0.9996))*180/Math.PI+Zone*6-183;
        longitude=Math.round(longitude*10000000);
        longitude=longitude/10000000;       
    }   
}