练习Calendar类（求未来10年的黑色星期五）

 1 package com.fj;
 2 
 3 import java.util.Calendar;
 4 
 5 public class BlackFriday {
 6     private static final int CURRENT_DAY = 13;
 7     public static void main(String[] args) {
 8         Calendar cal = Calendar.getInstance();
 9         int year = cal.get(Calendar.YEAR);
10         int month = cal.get(Calendar.MONTH);
11         for (int j = 0; j < 10; j++) {
12             for (int i = month; i < 12; i++) {
13                 cal.set(year, i, CURRENT_DAY);
14                 int a = cal.get(Calendar.DAY_OF_WEEK);
15                 if (a == 6) {
16                     System.out.println(cal.get(Calendar.YEAR)+"年"+(cal.get(Calendar.MONTH)+1) +"月"+ cal.get(Calendar.DAY_OF_MONTH)
17                             +"日 是黑色星期五");
18                 }
19             }
20             month = 0;
21             year++;
22         }
23     }
24 }