java - 泛型和性能问题

Question

我想知道是否有人可以查看我编写的类，我在 Eclipse 中收到一般警告，我只是想知道它是否可以被清理。我收到的所有警告都在下面的代码中用 ** 括起来。

该类采用 (hh:mm AM/PM) 形式的字符串列表，并将它们转换为 HourMinute 对象，以便查找列表中当前时间之后的第一个时间。

我也很好奇是否有更有效的方法来做到这一点。这很好用，但我内心的学生只是想知道如何才能做得更好。

public class FindTime {
    private String[] hourMinuteStringArray;

    public FindTime(String[] hourMinuteStringArray){
        this.hourMinuteStringArray = hourMinuteStringArray;
    }

    public int findTime(){

        HourMinuteList hourMinuteList = convertHMStringArrayToHMArray(hourMinuteStringArray);
        Calendar calendar = new GregorianCalendar();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);
        HourMinute now = new HourMinute(hour,minute);
        int nearestTimeIndex = findNearestTimeIndex(hourMinuteList, now);
        return nearestTimeIndex;
    }

    private int findNearestTimeIndex(HourMinuteList hourMinuteList, HourMinute now){
        HourMinute current;
        int position = 0;
        Iterator<HourMinute> iterator = **hourMinuteList.iterator()**;
        while(iterator.hasNext()){
            current = (HourMinute) iterator.next();
            if(now.compareTo(current) == -1){
                return position;
            }
            position++;
        }
        return position;
    }


    private static HourMinuteList convertHMStringArrayToHMArray(String[] times){
        FindTime s = new FindTime(new String[1]);
        HourMinuteList list = s.new HourMinuteList();
        String[] splitTime = new String[3];
        for(String time : times ){
            String[] tempFirst = time.split(":");
            String[] tempSecond = tempFirst[1].split(" ");
            splitTime[0] = tempFirst[0];
            splitTime[1] = tempSecond[0];
            splitTime[2] = tempSecond[1];
            int hour = Integer.parseInt(splitTime[0]);
            int minute = Integer.parseInt(splitTime[1]);
            HourMinute hm;
            if(splitTime[2] == "AM"){
                hm = s.new HourMinute(hour,minute);
            }
            else if((splitTime[2].equals("PM")) && (hour < 12)){
                hm = s.new HourMinute(hour + 12,minute);
            }
            else{
                hm = s.new HourMinute(hour,minute);
            }

            **list.add(hm);**
        }
        return list;
    }
    class **HourMinuteList** extends **ArrayList** implements RandomAccess{

    }
    class HourMinute implements **Comparable** {
        int hour;
        int minute;

        public HourMinute(int hour, int minute) {
            setHour(hour);
            setMinute(minute);
        }

        int getMinute() {
            return this.minute;
        }
        String getMinuteString(){
            if(this.minute < 10){
                return "0" + this.minute;
            }else{
                return "" + this.minute;
            }
        }

        int getHour() {
            return this.hour;
        }

        void setHour(int hour) {
            this.hour = hour;
        }

        void setMinute(int minute) {
            this.minute = minute;
        }

        @Override
        public int compareTo(Object aThat) {

            if (aThat instanceof HourMinute) {
                HourMinute that = (HourMinute) aThat;
                if (this.getHour() == that.getHour()) {
                    if (this.getMinute() > that.getMinute()) {
                        return 1;
                    } else if (this.getMinute() < that.getMinute()) {
                        return -1;
                    } else {
                        return 0;
                    }
                } else if (this.getHour() > that.getHour()) {
                    return 1;
                } else if (this.getHour() < that.getHour()) {
                    return -1;
                } else {
                    return 0;
                }
            }

            return 0;
        }

    }


If you have any questions let me know. 

Thanks, 
Rob

Answer 1

这是因为您没有为 List 和 Comparable 实例指定泛型，所以可以支持泛型。您可以使用以下方式重写代码:

class HourMinuteList extends ArrayList<HourMinute> implements RandomAccess{

}
class HourMinute implements Comparable<HourMinute> {

   public int compareTo(HourMinute aThat) {
   ....
  }
}

注意:泛型不是必需的，并且在运行时不使用，但最好使用它们，因为它可以帮助您避免代码中的一些错误。