NextSaturday.java

import java.util.Calendar;
import java.util.Date;

public class NextSaturdayMain {
	
	public static void main(String[] args) {
		
		System.out.println(getSaturday(new Date()));
		
	}
	
	public static long getSaturday(Date today) {
        Calendar cal = Calendar.getInstance();
        
        cal.setTime(today);

        int dow = cal.get(Calendar.DAY_OF_WEEK);
        
        while (dow != Calendar.SATURDAY) {
            int date = cal.get(Calendar.DATE);

            int month = cal.get(Calendar.MONTH);

            int year = cal.get(Calendar.YEAR);
            
            if (date == getMonthLastDate(month, year)) {
                
                if (month == Calendar.DECEMBER) {
                    month = Calendar.JANUARY;
                    
                    cal.set(Calendar.YEAR, year + 1);
                } else {
                    month++;
                }
                
                cal.set(Calendar.MONTH, month);
                
                date = 1;
            } else {
                date++;
            }
            
            cal.set(Calendar.DATE, date);
            
            dow = cal.get(Calendar.DAY_OF_WEEK);
        }
        System.out.println(cal.getTime());
        return cal.getTimeInMillis();
    }

    private static int getMonthLastDate(int month, int year) {
        switch (month) {
            case Calendar.JANUARY:  
            case Calendar.MARCH:
            case Calendar.MAY:
            case Calendar.JULY:
            case Calendar.AUGUST:
            case Calendar.OCTOBER:
            case Calendar.DECEMBER:
                return 31;

            case Calendar.APRIL:
            case Calendar.JUNE:
            case Calendar.SEPTEMBER:
            case Calendar.NOVEMBER:
                return 30;
                
            default:    //  Calendar.FEBRUARY
                return year % 4 == 0 ? 29 : 28;
        }
    }

}