Calendar類常用方法

Calendar常量

Calendar cal = Calendar.getInstance();
cal.get(Calendar.DATE);//-----------------------當天 1-31
cal.get(Calendar.DAY_OF_MONTH);//---------------當天 1-31 ，這個相對而言會比較準確
cal.get(Calendar.DAY_OF_WEEK);//----------------從星期天開始計算，如果今天星期二，那麼返回3
cal.get(Calendar.DAY_OF_YEAR);
cal.get(Calendar.HOUR);//-----------------------12小時制
cal.get(Calendar.HOUR_OF_DAY);//----------------24小時制，一般使用這個屬性賦值
cal.get(Calendar.MILLISECOND);
cal.get(Calendar.MINUTE);
cal.get(Calendar.SECOND);
cal.get(Calendar.WEEK_OF_MONTH);
cal.get(Calendar.WEEK_OF_YEAR);
cal.get(Calendar.MONTH);//-----------------------月份獲取需要 +1，那麼，賦值時需要 -1
cal.get(Calendar.YEAR);

用法示例

public static String heartbeat() {
        String year = String.valueOf(Calendar.getInstance().get(Calendar.YEAR));
        String month = String.valueOf(Calendar.getInstance().get(Calendar.MONTH) + 1);
        String day = String.valueOf(Calendar.getInstance().get(Calendar.DAY_OF_MONTH));
        String hour = String.valueOf(Calendar.getInstance().get(Calendar.HOUR_OF_DAY));
        String minute = String.valueOf(Calendar.getInstance().get(Calendar.MINUTE));
        String second = String.valueOf(Calendar.getInstance().get(Calendar.SECOND));

        if (month.length() < 2) month = "0" + month;
        if (day.length() < 2) day = "0" + day;
        if (hour.length() < 2) hour = "0" + hour;
        if (minute.length() < 2) minute = "0" + minute;
        if (second.length() < 2) second = "0" + second;

        return year + "-" + month + "-" + day + " " + hour + ":"
                + minute + ":" + second + " - " + "I'm alive!\n";
    }

    public static void main(String[] args) throws Exception {
        System.out.print(heartbeat());
    }