程式碼

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * Created by qqg on 2017/12/26.
 */
public class Times {
    public String addTime(Date date,int hour){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.HOUR_OF_DAY,hour);
        SimpleDateFormat sdf = new
 
 SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        /*try {
            Date date1 = sdf.parse(sdf.format(calendar.getTime()));
            return  date1;
        } catch (ParseException e) {
            e.printStackTrace();
        }*/
        return sdf.format(calendar.getTime());
    }

    public static
 
 void main(String[] args) {
        Times times = new Times();
        Date date = new Date();
        System.out.println(times.addTime(date,-8));
    }
}

傳入的引數為正時是加，負時是減。