2012-09-10 141 views
4

我遇到了Java日曆的一個奇怪問題。日曆小時數設置爲0,但顯示1,爲什麼?

以下代碼從午夜開始的日期連續添加3小時。

public static void main(String[] args) { 

    Calendar now = Calendar.getInstance(TimeZone.getTimeZone("GMT+0")); 

    // Setting to January 29th, 1920 at 00:00:00 
    // now.setTimeZone(TimeZone.getTimeZone("GMT+0")); 
    now.set(Calendar.YEAR, 1920); 
    now.set(Calendar.MONTH, 0); 
    now.set(Calendar.DAY_OF_MONTH, 29); 
    now.set(Calendar.HOUR_OF_DAY, 0); 
    now.set(Calendar.MINUTE, 0); 
    now.set(Calendar.SECOND, 0); 
    now.set(Calendar.MILLISECOND, 0);  

    now.setLenient(false); 

    int threeHours = 1000 * 60 * 60 * 3; 

    SimpleDateFormat sdf 
     = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss SSS"); 

    for (int i=0;i<25;i++) { 

     System.out.println(sdf.format(now.getTime())); 
     now.add(Calendar.MILLISECOND, threeHours); 

    } 

} 

然而,所顯示的結果是:

1920-01-29 01:00:00 000 
1920-01-29 04:00:00 000 
1920-01-29 07:00:00 000 
1920-01-29 10:00:00 000 
1920-01-29 13:00:00 000 
1920-01-29 16:00:00 000 
1920-01-29 19:00:00 000 
1920-01-29 22:00:00 000 
1920-01-30 01:00:00 000 
1920-01-30 04:00:00 000 
1920-01-30 07:00:00 000 
1920-01-30 10:00:00 000 
1920-01-30 13:00:00 000 
1920-01-30 16:00:00 000 
1920-01-30 19:00:00 000 
1920-01-30 22:00:00 000 
1920-01-31 01:00:00 000 
1920-01-31 04:00:00 000 
1920-01-31 07:00:00 000 
1920-01-31 10:00:00 000 
1920-01-31 13:00:00 000 
1920-01-31 16:00:00 000 
1920-01-31 19:00:00 000 
1920-01-31 22:00:00 000 
1920-02-01 01:00:00 000 

爲什麼第一個小時1也不是0?我位於GMT + 1,這可能是相關的嗎?

+1

夏令時也許? – BigMike

+0

你有沒有考慮過使用jodatime? – fmsf

+0

@BigMike我無法在日曆中找到任何有關日光的方法... – JVerstry

回答

4

使用now.getTime()得到的Date沒有時區。

嘗試用

sdf.setTimeZone(now.getTimeZone()); 
+1

不錯,我今天學到了一些東西... – JVerstry

1

現在設置時區,應該很好地工作

 Calendar now = Calendar.getInstance(); 
     TimeZone timezone = TimeZone.getTimeZone("GMT+0"); 
     now.set(Calendar.YEAR, 1920); 
     now.set(Calendar.MONTH, 0); 
     now.set(Calendar.DAY_OF_MONTH, 29); 
     now.set(Calendar.HOUR_OF_DAY, 0); 
     now.set(Calendar.MINUTE, 0); 
     now.set(Calendar.SECOND, 0); 
     now.set(Calendar.MILLISECOND, 0);  
     now.setLenient(false); 
     int threeHours = 1000 * 60 * 60 * 3; 
     SimpleDateFormat sdf 
      = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss SSS"); 
     sdf.setTimeZone(timezone); 
     for (int i=0;i<25;i++) { 
      System.out.println(sdf.format(now.getTime())); 
      now.add(Calendar.MILLISECOND, threeHours); 
     } 
1

我猜你應該使用 now.set(Calendar.HOUR,0);而不是now.set(Calendar.HOUR_OF_DAY,0);