字符串和Date互相转化

话不多说，上程序，如图：

public class TestDate {
    public static void main(String[] args) throws ParseException {
        String str = "2016-6-28 8:00:00";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        //字符串转Date
        Date date = sdf.parse(str);
        //Date转字符串
        str = sdf.format(date);

        System.out.println(date);
        System.out.println(str);
    }
}

结果:

Tue Jun 28 08:00:00 CST 2016
2016-06-28 08:00:00

打印昨天的当前时刻

public class YesterdayCurrent {
    public static void main(String[] args){
        Calendar cal = Calendar.getInstance();
        cal.add(Calendar.DATE, -1);
        System.out.println(cal.getTime());
    }
}