java - 似乎无法按日期对对象数组进行排序

Question

class newPlanner{

    private  newAppointment[] Appoint = new newAppointment[20];

    newPlanner(){
        newAppointment obj1 = new newAppointment("Mar",4,17,30,"Quiz 1");

        newAppointment obj2 = new newAppointment("Apr",1,17,30,"Midterm");

        newAppointment obj3 = new newAppointment("May",6,17,30,"Quiz 2");

        newAppointment obj4 = new newAppointment("Jun",3,17,30,"Final");

        Appoint [0] = obj4;
        Appoint [1] = obj3;
        Appoint [2] = obj2;
        Appoint [3] = obj1;

    }

    public void runMethod(){
        boolean answer = true;

        while (answer) {
            System.out.println("Select an Option. ");
            System.out.println(" 1. Add Appointment ");  
            System.out.println(" 2. List Appointment ");
            System.out.println(" 3. Delete Appointment ");
            System.out.println(" 4. Exit ");

这是我的代码，我需要创建一个方法来移动数组元素以插入新约会并删除约会。该数组需要按日期排序，但我似乎无法得到它，请帮助

Answer 1

您可以使用 Arrays.sort(T[] a,Comparator<? super T> c) 对数组进行就地排序，其中T是你的Appointment类。

您将需要实现 Comparator Appointment的接口(interface)。如果您的 Appointment 这会容易得多类(class)参加了 Date 构造函数中的对象；那么你的比较器就是:

Arrays.sort(appointments, new Comparator<Appointment>{

    @Override
    public int compare(Appointment appointment1, Appointment appointment2){
        return appointment1.getDate().compareTo(appointment2.getDate());
    }
});

您可以确定 Appointment 的日期类如下:

public class Appointment{
    /**
    * three letter month
    */
    private final String month;

    /**
    * one to two digit day e.g. 1 or 12,
    */
    private final int day;

    /**
    * two digit military time hour e.g. 01, 11, 17
    */
    private final int hour;

    /**
    * lazily instantiated appointment Date
    */
    private Date date;

    //..

    public class Appointment(String month, int day, int hour /*other parameters*/){
        this.month = month;
        this.day = day;
        this.hour = hour;

        calculateDate();
    }

    private void caculateDate(){
        String dateString = String.format("%d %s 2018 %d",day,month,hour);
        SimpleDateFormat dateFormat = new SimpleDateFormat("d MMM yyyy HH");

        try{
            this.date = dateFormat.parse(dateString);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    public Date getDate(){
        return date;
    }
}