給周編號和年份找到星期的第一天和最後一天

Question

我有周數和年份，我想要得到星期的第一天和最後一天的日期，這是我的代碼，它給出我錯了結果，請告訴我我做錯了什麼。提前致謝。

SimpleDateFormat dt = new SimpleDateFormat("dd/mm/yyyy"); 
String start =""; 
String end =""; 
int week = 38; 
int yeat = 2016; 
Calendar calendar = Calendar.getInstance(); 
calendar.set(Calendar.WEEK_OF_YEAR, week); 
calendar.set(Calendar.YEAR, year); 
// firt day of week 
start = dt.format(calendar.getTime()); 
calendar.add(Calendar.DAY_OF_MONTH, 6); 
//last day of week 
end = dt.format(calendar.getTime()); 

Answer 1

• 更正DateFormatter語法，一個月應該在死刑案件

• 獲取週日和週六日起在特定的一週中， 一年過去了。

  SimpleDateFormat dt = new SimpleDateFormat("dd/MM/yyyy"); 
      String start =""; 
      String end =""; 
      int week = 38; 
      int year = 2016; 
      Calendar calendar = Calendar.getInstance(); 
      calendar.set(Calendar.YEAR, year); 
      calendar.set(Calendar.DAY_OF_WEEK,Calendar.SUNDAY); 
      calendar.set(Calendar.WEEK_OF_YEAR, week); 
       start = dt.format(calendar.getTime()); 
      calendar.set(Calendar.DAY_OF_WEEK,Calendar.SATURDAY); 
       end = dt.format(calendar.getTime()); 
      System.out.println(start+" |"+end); 
  

Answer 2

如果您使用Java 8+，你可以使用內置的週日期格式：

int week = 38; 
int year = 2016; 
String weekYear = year + "-W" + week + "-7"; //2016-W38-7 
LocalDate d = LocalDate.parse(year + "-W" + week + "-7", ISO_WEEK_DATE); //2016-09-25 

注：-7在字符串的結尾表示一週的最後一天（即星期日）。

Answer 3

試試這個：

SimpleDateFormat dt = new SimpleDateFormat("dd/mm/yyyy"); 
String start =""; 
String end =""; 
int week = 38; 
int year = 2016; 
Calendar calendar = Calendar.getInstance(); 
calendar.set(Calendar.WEEK_OF_YEAR, week); 
calendar.set(Calendar.YEAR, year); 

// firt day of week 
Calendar cal = calendar; 
while (cal.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY) { 
    cal.add(Calendar.DATE, -1); 
} 
start = dt.format(cal.getTime()); 
System.out.println(start); 

Calendar cal1 = calendar; 
while (cal1.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY) { 
    cal1.add(Calendar.DATE, 1); 
} 
//last day of week 
end = dt.format(cal1.getTime()); 
System.out.println(end);