Simple ejemplo de cómo hacer cálculo de días corrientes y laborales.

Calculo.java

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;

public class Calculo {

  public static final String formatofecha = "dd/MM/yyyy";
	public static final String letraescape = "x";

	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);
		SimpleDateFormat df = new SimpleDateFormat(formatofecha); // día mes año
		df.setLenient(false);

		try {
			do {
				String fechap = ask(scanner, "FECHA DE INICIO: (" + formatofecha + " o '"
						+ letraescape + "' para salir) : ");
				String diasp = ask(scanner, "DIAS : ");

				if (fechap != null && diasp != null) {
					
					try {
						Date fecha = df.parse(fechap);
						Integer dias = Integer.parseInt(diasp);

						/* Para depurar más fácil
						 * System.out.println("Cadena original: " + fechap);
						 * System.out.println("Fecha interpretada: " +
						 * date.toString()); System.out.println();
						 */

						System.out.println("Cálculo de " + dias + " dias para la fecha: "
								+ fecha.toString());
						
						System.out.println();
						
						Date fecha1 = calculateEndDate(fecha, dias);
						Date fecha2 = calculateWorkedEndDate(fecha, dias);

						System.out.println(dias + " días calendario: "
								+ fecha1.toString());
						System.out.println(dias + " días laborados: "
								+ fecha2.toString());

					} catch (NumberFormatException ne) {
						System.out.println("ERROR: mal formato \"" + diasp
								+ "\"");
					} catch (ParseException pe) {
						System.out.println("ERROR: mal formato \"" + fechap
								+ "\"");
					}
				} else {
					;
				}

			} while (true);
		} catch (Exception e) {
			;
		}
	}
	
	public static String ask(final Scanner scanner, final String copy) {
		System.out.print(copy);
		String parse = scanner.next();
		if (parse != null)
			parse = parse.trim();
		if (parse == null || parse.length() == 0)
			return null;
		if (parse.equalsIgnoreCase(letraescape))
			return null;

		return parse;
	}

	public static Date calculateWorkedEndDate(Date startDate, int duration) {
		Calendar startCal = Calendar.getInstance();

		startCal.setTime(startDate);
		for (int i = 1; i < duration; i++) {
			startCal.add(Calendar.DAY_OF_MONTH, 1);
			while (startCal.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY
					|| startCal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
				startCal.add(Calendar.DAY_OF_MONTH, 1);
			}
		}

		return startCal.getTime();
	}

	public static int calculateWorkDuration(Date startDate, Date endDate) {
		Calendar startCal = Calendar.getInstance();
		startCal.setTime(startDate);

		Calendar endCal = Calendar.getInstance();
		endCal.setTime(endDate);

		int workDays = 0;

		if (startCal.getTimeInMillis() > endCal.getTimeInMillis()) {
			startCal.setTime(endDate);
			endCal.setTime(startDate);
		}

		do {
			startCal.add(Calendar.DAY_OF_MONTH, 1);
			if (startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY
					&& startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY) {
				workDays++;
			}
		} while (startCal.getTimeInMillis() <= endCal.getTimeInMillis());

		return workDays;
	}

	public static Date calculateEndDate(Date startDate, int duration) {
		Calendar startCal = Calendar.getInstance();

		startCal.setTime(startDate);
		for (int i = 1; i < duration; i++) {
			startCal.add(Calendar.DAY_OF_MONTH, 1);
		}

		return startCal.getTime();
	}

}