how to pass a String to another String variable in another class?

i have this :

 @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

        String urlCorrecta="";


        //Si se escoge la posicion de el arreglo 0 abre la clase LasVegas
        if (position == 0)
        {
            Intent intent = new Intent(this, MainActivity.class);
            startActivity(intent);
            urlCorrecta = "souphttpsrc location=http://ift.tt/1CdC9SR ! multipartdemux single-stream=true ! jpegdec ! autovideosink sync=false ";


        }

        //Si se escoge la posicion de el arreglo 1 abre la clase LosGuayabos
        else if (position == 1)

        {
            Intent intent = new Intent(this, LosGuayabos.class);
            startActivity(intent);

            urlCorrecta = "souphttpsrc location=http://ift.tt/1ArO2O0 ! multipartdemux single-stream=true ! jpegdec ! autovideosink sync=false ";

        }

        //Si se escoge la posicion de el arreglo 2 abre la clase RegionalNorte
        else if (position == 2)

        {
            Intent intent = new Intent(this, RegionalNorte.class);
            startActivity(intent);

            urlCorrecta = "souphttpsrc location=http://ift.tt/1CdCa97 ! multipartdemux single-stream=true ! jpegdec ! autovideosink sync=false ";
        }


        //Si se escoge la posicion de el arreglo 3 abre la clase RegionalSur
        else if (position == 3)

        {
            Intent intent = new Intent(this, RegionalSur.class);
            startActivity(intent);

            urlCorrecta = "souphttpsrc location=http://ift.tt/1ArO5cJ ! multipartdemux single-stream=true ! jpegdec ! autovideosink sync=false ";

        }

    }

i want to pass the value of the String urlCorrecta to the String VIDEO_IN_PIPELINE located in the class MainActivity.

public class MainActivity extends ActionBarActivity implements SurfaceHolder.Callback{




    private final String VIDEO_IN_PIPELINE = VALUE OF THE STRING urlCorrecta;
    private final String HOST_IP = "192.168.1.167";

}

How can i take that String from the other class to this one?

thanks very much for reading.