Question

我的课程Appointment包含字段：

int day
int month
int year
String desc

这会存储约会的描述以及日期。

超级班Appointment：

public class Appointment {
    int dayNum;
    int monthNum;
    int yearNum;
    String desc;

    public Appointment(String des, int day) {
        //Monthly Appointments (Check day)
        desc = des;
        dayNum = day;
    }
    public Appointment(String des, int day, int month){
        //Yearly Appointments (Check day AND month)   
        desc = des;
        dayNum = day;
        monthNum = month;
    }
    public Appointment(String des, int day, int month, int year){
        //One Time (Check All)
        desc = des;
        dayNum = day;
        monthNum = month;
        yearNum = year;
    }     
}

以下是我的3个子类：

一次约会： Onetime

public class OneTime extends Appointment{
    public OneTime(String des, int day, int month, int year){
        super(des, day, month, year);
    }
    public String getDesc(){
        return desc;
    }
}

每月一次约会： Monthly

public class Monthly extends Appointment{
    public Monthly(String des, int monum){
        super(des, monum);
    }
    public String getDesc(){
        return desc;
    }
}

每年一次约会 Yearly

public class Yearly extends Appointment{
    public Yearly(String des, int day, int month){
        super(des, day, month);
    }
    public String getDesc(){
        return desc;
    }
}

问题：我被要求向Appointment添加少量ArrayList个对象（我知道）。但是，我必须编写一个方法occursOn(int day, int month, int year)，它返回当天的所有约会。我不确定的部分是编写occursOn()方法。假设我有一个关于11/22/2018的约会，我如何将每月对象与day参数/ Yearly与月和日参数/ OneTime进行比较，与所有参数进行比较？

教科书问题：＆＃34;实现超类Appointment和子类Onetime，Daily和Monthly。约会有一个描述（例如，＆＃34;见牙医＆＃34;）和日期。编写方法occursOn(int year, int month, int day)，检查约会是否在该日期发生。例如，对于每月预约，您必须检查当月的日期是否匹配。然后使用混合约会填充Appointment个对象的数组。让用户输入日期并打印出该日期发生的所有约会。＆＃34;

注意：这不是我的功课。我只是在2个小时内对此进行了单元测试而且卡住了。

Answer 1

首先，您可能希望声明Appointment abstract，以便sublcasses必须实现一些方法：

 public abstract class Appointment {

        int dayNum;
        int monthNum;
        int yearNum;
        String desc;

        public Appointment(String des, int day){desc = des; dayNum = day;} //Monthly Appointments (Check day)
        public Appointment(String des, int day, int month){desc = des; dayNum = day; monthNum = month;} //Yearly Appointments (Check day AND month)   
        public Appointment(String des, int day, int month, int year){desc = des; dayNum = day; monthNum = month; yearNum = year;} //One Time (Check All)    

        abstract boolean occursOn(int day, int month, int year);

        abstract String getDesc();

        }

然后，您班级中occursOn的实施可能是：

<强>每月

    boolean occursOn(int day, int month, int year){

                return (this.day == day);
}

<强>每年

    boolean occursOn(int day, int month, int year){

        return (this.day == day) && (this.month == month);
}

OneTime

    boolean occursOn(int day, int month, int year){

                return (this.day == day) && (this.month == month) && (this.year == year);
}

最后，假设appointments是一个List，你填充了各种子类实例，有一个通用方法（可能在你的主类中），它将返回所有相应的{{ 1}}对象：

Appointment

Answer 2

一种方法是使用＆＃34; date＆＃34;具有可选值的键，例如像这样：

class DateKey {
  int day; //always needed
  Integer month; //null in case of monthlies
  Integer year; //null in case of monthlies and yearlies

  //override equals() and hashCode()
}

使用地图的日期键：

//handling this would be easier with Google Guava's Multimap, if you may use it
Map<DateKey, List<Appointment>> appointments = ...;

然后使用3步查找：

List<Appointment> onetimes = appointments.get(new DateKey( day, month, year) );
List<Appointment> yearlies= appointments.get(new DateKey( day, month, null) );
List<Appointment> monthlies = appointments.get(new DateKey( day, null, null) );

最后结合3个列表。

最后，DateKey也可以成为Appointment类的一部分，这将使映射更加一致。我可能会使用稍微不同的名称（想想一个），因为它不仅仅是一个地图键了。

Answer 3

您可以在Appointment类中添加一个方法，用于确定约会是否在这样的给定日期开启。

public class Appointment {

    int dayNum;
    int monthNum;
    int yearNum;
    String desc;

    public Appointment(String des, int day){desc = des; dayNum = day;} //Monthly Appointments (Check day)
    public Appointment(String des, int day, int month){desc = des; dayNum = day; monthNum = month;} //Yearly Appointments (Check day AND month)
    public Appointment(String des, int day, int month, int year){desc = des; dayNum = day; monthNum = month; yearNum = year;} //One Time (Check All)

    boolean occuresOn(int day, int month, int year){
        if( (this.dayNum == day) && (this.monthNum == month) && (this.yearNum == year))
            return true;

        return false;

    }
}

并在子类中覆盖此功能。

public class Monthly extends Appointment{

    public Monthly(String des, int monum){
        super(des, monum);
    }
    public String getDesc(){
        return desc;
    }

    boolean occuresOn(int day, int month, int year){
        if( (this.dayNum == day) )
            return true;

        return false;

    }
}

public class Yearly extends Appointment{

    public Yearly(String des, int day, int month){
        super(des, day, month);
    }
    public String getDesc(){
        return desc;
    }

    boolean occuresOn(int day, int month, int year){
        if( (this.dayNum == day) && (this.monthNum == month))
            return true;

        return false;

    }
}

现在你可以迭代你的约会并找到那些约会日期：

List<Appointment> aps = new ArrayList<>(); //initialize this
    for (Appointment ap : aps){
        if(ap.occuresOn(2, 3, 2016))
            ....
    }

Answer 4

OccursOn（）

应该是超类中的抽象方法（约会）。你的每个子类都必须相应地实现它。

一次 - 检查日，月和年。

每月 - 仅限查看日。

每年 - 检查日期和月份。

子类问题（JAVA）

4 个答案: