Data

import java.util.*;
import java.text.*;

class AdicionarData {
    public static Date adicionar (Date dt, int dias) {
        Calendar cal = Calendar.getInstance();
        cal.setTime (dt);
        cal.add (Calendar.DATE, dias);
        return cal.getTime();
    }

    public static void main(String[] args) {
        Date atual = new Date();
        SimpleDateFormat f = new SimpleDateFormat("dd/MM/yyyy");
        String sData = f.format(atual);//como faço pra adiconar 3 dia ??
        Date daquiA3Dias = adicionar (atual, 3);
        System.out.println (f.format (daquiA3Dias));
    }
}

Date atual = new Date();

SimpleDateFormat f = new SimpleDateFormat(“dd/MM/yyyy”);

atual.setTime(atual.getTime() + (1 * 60 * 60 * 1000 * 24 * 3));

String sData = f.format(atual);

System.out.println(sData);

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

public class DateUtil {
	
	public static final String LOCAL_DATE_PATTERN = "dd/MM/yyyy";

	private DateUtil() {
	}
	
	public static Date addDaysInSystemDate(int days){
		SimpleDateFormat sdf = new SimpleDateFormat(LOCAL_DATE_PATTERN);
		Calendar calendar = Calendar.getInstance(); 
		System.out.println("SystemDate : " + sdf.format(calendar.getTime()));
		calendar.add(Calendar.DATE, days);
		System.out.println("Date + " + days + " days is : " + sdf.format(calendar.getTime()));
		return calendar.getTime();
	}

}

SimpleDateFormat f = new SimpleDateFormat("dd/MM/yyyy"); 
Date dt = f.parse ("27/05/2007");