java - 我无法弄清楚 getTotalFlightTime()

Question

Itinerary 类通过以下成员存储有关行程的信息:

• 名为 Flights 的私有(private) ArrayList 数据字段，其中包含以下行程的航类出发时间递增顺序。 (提示:您不需要进行排序。)

• 一个构造函数，用于创建包含 ArrayList 类型中的指定航类的行程。

• 名为 getTotalFlightTime() 的方法，返回行程的总飞行时间(以分钟为单位)。(提示:为每个 Flight 对象调用 getFlightTime() 方法。)

• 名为 getTotalTravelTime() 的方法，返回从行程中首个航类的起飞时间至最后一个航类的到达时间。假设所有的时间位于同一时区。

package que6;

/**
 *
 * @author vpi764
 */


import java.util.ArrayList;
import java.util.GregorianCalendar;
public class TestFlightItinerary {


    public static void main(String[] args) {

  lic static void main(String[] args) {
        ArrayList<Flight>flights = new ArrayList<>();
  Flight F1 =  new Flight("US230", new GregorianCalendar(2014, 5, 5, 5, 5, 0), new GregorianCalendar(2014, 5, 5, 6, 15, 0));
    Flight F2 =  new Flight("US235", new GregorianCalendar(2014, 5, 5, 6, 55, 0), new GregorianCalendar(2014, 5, 5, 7, 45, 0));
      Flight F3 =  new Flight("US237", new GregorianCalendar(2014, 5, 5, 9, 35, 0), new GregorianCalendar(2014, 5, 5, 12, 55, 0));

      flights.add(F1);
      flights.add(F2);
      flights.add(F3);

 }

}

class Flight{

        private String flightNo;
        private GregorianCalendar departureTime;
        private GregorianCalendar arrivalTime;


        //Constructor
        Flight(String SpecNo,GregorianCalendar SpecDtime ,GregorianCalendar SpecAtime ){
            this.flightNo = SpecNo;
            this.departureTime = SpecDtime;
            this.arrivalTime = SpecAtime;
        }
        //Getters
        public String GetFlightNo() {
            return flightNo;
        }
        public GregorianCalendar GetDtime() {
            return departureTime;
        }
        public GregorianCalendar GetAtime() {
            return arrivalTime;
        }

        //setters
        // If we don't use setter the could would still work because we are getting input in constructor with parameters
        public void SetFlightNo(String Number) {
            flightNo = Number;
        }
        public void SetDtime(GregorianCalendar Dtime) {
            departureTime = Dtime;
        }
        public void SetAtime(GregorianCalendar Atime) {
            arrivalTime = Atime;
        }

        public long getTimeinMillis() {
                return (arrivalTime.getTimeInMillis() - departureTime.getTimeInMillis());
                }
                // getFlightTime method
                public long getFlightTime() {
                return getTimeinMillis() / (60 * 1000);
                }
    }

class Itinerary {


    ArrayList<Flight> flights = new ArrayList<>();

   public Itinerary(){
           this.flights = flights;
    }
    public long getTotalFlightTime(ArrayList<Flight> flights){

    }
    public long getTotalTravelTime(){

    }


}

Answer 1

ArrayList 维护元素添加的顺序。也许这就是暗示。