java - 以数组形式跟踪田径运动时间

Question

我正在构建一个java系统来记录运动员所用的时间并将其存储在一个数组中。约束如下

1. 从A点到B点，记录出发时间和到达B点的时间。
2. 记录从B点出发的时间和到达A点的时间。
3. 应计算各点之间花费的时间
4. 该练习每周进行 7 天。

我只能弄清楚如何录制一种方式。如何追踪每个人每天的出发和到达情况？代码:

public class ArrayLesson {

    static int[] departuretime = new int[7];
    static int sum = 0;
    static double ave = 0;

    public static void main(String[] args) {
        departuretime[0] = 07;
        departuretime[1] = 20;
        departuretime[2] = 40;
        departuretime[3] = 12;
        departuretime[4] = 10;
        departuretime[5] = 12;
        departuretime[6] = 11;

        System.out.println("index      Value");//headings
        for (int i = 0; i < departuretime.length; i++) {
            sum = departuretime[i] + sum;
            System.out.printf("%5d%8d%n", i, sum);
        }
        System.out.println("Weekly total:" + sum);
        System.out.println("weekly average:" + sum / departuretime.length);
    }

}

Answer 1

好的，这是我对这个问题的看法:

首先，数组在这里并不是最好的数据结构。不要使用数组索引来表示应用程序域数据。数组非常适合表示相同项目的复制。如果您需要开始和结束，请使用“开始”和“结束”变量，不要使用索引 0 和 1 来表示。

其次，如果您需要记录和比较日期/时间，可以使用内置的 java 类来完成此操作。所以使用它们。这包括诸如时间间隔、星期枚举等概念

所以我的解决方案如下

1) 创建一个数据结构来保存单向的开始结束记录时间。这是计算持续时间的地方:

import java.time.*;
import java.time.format.DateTimeFormatter;

// records start and end times for one direction
public class RecordedTrack {

    public LocalTime start;
    public LocalTime end;

    public RecordedTrack (LocalTime start, LocalTime end) {
        this.start = start;
        this.end = end;
    }

    // accept String times in "HH:MM:SS" format 
    public RecordedTrack (String start, String end) {
        this(
            LocalTime.parse(start, DateTimeFormatter.ISO_LOCAL_TIME),
            LocalTime.parse(end, DateTimeFormatter.ISO_LOCAL_TIME));
    }

    public Duration getDuration() {
        return Duration.between(start, end);
    }

    // return String times in "MM:SS" format 
    public String getDurationStr () {
        long seconds = getDuration().getSeconds();
        return String.format("%02d:%02d", (seconds % 3600) / 60, seconds % 60);
    }
}

2)创建一个数据结构来保存两个方向的完整行程:

// records start and end times for complete two directions itinerary
public class RecordedItinerary {

    public RecordedTrack AtoB;
    public RecordedTrack BtoA;

    public RecordedItinerary (RecordedTrack AtoB, RecordedTrack BtoA) {
        this.AtoB = AtoB;
        this.BtoA = BtoA;
    }
}

3) 创建一个数据结构来保存与一个人相关的所有数据。我假设一个人有一个名字来区别于其他人，并进行一项日常体育锻炼。如果需要的话可以修改:

// records weekly itineraries of one person 
public class Person {

    public String name;
    public RecordedItinerary[] weeklyItineraries = new RecordedItinerary[DayOfWeek.values().length+1]; 

    public Person (String name) {
        this.name = name;
    }

    // add an itinerary of given day-of-week
    public void addDailyItinerary(DayOfWeek dow, RecordedItinerary itinerary) {
        weeklyItineraries[dow.getValue()] = itinerary;
    }
    // add today's itinerary
    public void addDailyItinerary(RecordedItinerary itinerary) {
        addDailyItinerary(LocalDateTime.now().getDayOfWeek(), itinerary);
    }

    // get an itinerary of given day-of-week 
    public RecordedItinerary getDailyItinerary(DayOfWeek dow) {
        return weeklyItineraries[dow.getValue()];
    }
    // get today's itinerary
    public RecordedItinerary getDailyItinerary() {
        return getDailyItinerary(LocalDateTime.now().getDayOfWeek());
    }

    // a person is identified by his/her name
    // will throw ClassCastException if arg is not a Person
    @Override
    public boolean equals(Object o) {
        return this.name.equals(((Person)o).name);
    }
}

4) 现在您可以根据输入创建 Person 实例。您需要将它们保存在 map 或您喜欢的任何数据结构中。下面是一个测试程序，展示了系统的工作原理:

public class RecordingTimesSystem {

    public static void main(String... args) {
        // new person!
        Person john = new Person("John Doe");
        // add today's two-direction itinerary 
        john.addDailyItinerary(
            new RecordedItinerary(
                new RecordedTrack("07:10:00", "07:20:30"), // a-to-b recorded times
                new RecordedTrack("09:30:00", "09:37:00")) // b-to-a recorded times
        );

        DayOfWeek requestedDayOfWeek = LocalDateTime.now().getDayOfWeek();
        System.out.println(john.name + " " + requestedDayOfWeek.toString() + 
                " AtoB: " + 
                john.getDailyItinerary().AtoB.getDuration().getSeconds() + " (sec) " +  
                john.getDailyItinerary().AtoB.getDurationStr() + " (mm:ss)");
        System.out.println(john.name + " " + requestedDayOfWeek.toString() + 
                " BtoA: " + 
                john.getDailyItinerary().BtoA.getDuration().getSeconds() + " (sec) " +  
                john.getDailyItinerary().BtoA.getDurationStr() + " (mm:ss)");
    }
}

输出:

John Doe SUNDAY AtoB: 630 (sec) 10:30 (mm:ss)
John Doe SUNDAY BtoA: 420 (sec) 07:00 (mm:ss)