Calendar、SimpleDateFormat 时间用法

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public static void main(String[] args) {

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

        Calendar cal = Calendar.getInstance();

        cal.add(Calendar.YEAR, 0);//年

        cal.add(Calendar.MONTH, 0);//月

        cal.add(Calendar.DATE, -1);//日,比当前时间小1天

        cal.add(Calendar.HOUR_OF_DAY, -1);//时,HOUR_OF_DAY是24小时制，HOUR是12小时制

        cal.add(Calendar.MINUTE, 0);//分

        cal.add(Calendar.SECOND, 0);//秒

        Date time = cal.getTime();

        System.out.println(sdf.format(time));

    }

 

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public static void main(String[] args) {

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

        Calendar cal = Calendar.getInstance();//得到当前时间

        cal.set(2013, 5, 4, 13, 44, 51);//年月日时分秒(月份0代表1月)

        cal.set(Calendar.YEAR, 2014);//年

        cal.set(Calendar.MONTH, 7);//月(月份0代表1月)

        cal.set(Calendar.DATE, 11);//日

        cal.set(Calendar.HOUR_OF_DAY, 15);//时

        cal.set(Calendar.MINUTE, 33);//分

        cal.set(Calendar.SECOND, 32);//秒

        Date time = cal.getTime();

        System.out.println(sdf.format(time));//2014-08-11 15:33:32

    }