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算法练习(24):日期类设计(1.2.11-1.2.12)

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kyson老师的算法之路
2017.09.27 12:38* 字数 382

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算法(第4版)

知识点

  • 日期类的设计
  • 异常处理
  • 蔡勒公式

题目

1.2.11 根据Date的API实现一个SmartDate类型,在日期非法时抛出一个异常。


1.2.11 Develop an implementation SmartDate of our Date API that raises an excep- tion if the date is not legal.

答案

public class SmartDate {
    
    @SuppressWarnings("unused")
    private final int year;
    @SuppressWarnings("unused")
    private final int month;
    @SuppressWarnings("unused")
    private final int day;
    
    public SmartDate(int year,int month,int day) throws Exception {
        if (year < 0 || month < 0 || day < 0) {
            Exception exception = new Exception("年月日要大于0");
            throw exception;
        }
        if (month > 12) {
            Exception exception = new Exception("年份要小于等于12");
            throw exception;
        }
        
        switch (month) {
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
        case 1:{
            if (day > 31) {
                Exception exception = new Exception(month + "月小于31号");
                throw exception;
            }
        }
            break;
        case 2:{
            if (day > 29) {
                Exception exception = new Exception(month + "月小于31号");
                throw exception;
            }
            
            int leapYear = year % 4;
            if (leapYear != 0) {
                if (day > 28) {
                    Exception exception = new Exception(month + "月小于29号");
                    throw exception;
                }
            }
            
        }
            break;
        case 4:
        case 6:
        case 9:
        case 11:{
            if (day > 30) {
                Exception exception = new Exception(month + "月小于30号");
                throw exception;
            }
        }
            break;
            

        default:
            break;
        }
        

        
        this.day    = day;
        this.year   = year;
        this.month  = month;
    }
    

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        SmartDate date = new SmartDate(2007, 1, 50);
    }

}

代码索引

SmartDate1.java

视频讲解

点此观看分析视频

题目

1.2.12 为SmartDate添加一个方法dayOfTheWeek(),为日期中每周的日返回Monday、Tuesday、Wednesday、Thursday……假定是21世纪


1.2.12 Add a method dayOfTheWeek() to SmartDate that returns a String value Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday, giving the ap- propriate day of the week for the date. You may assume that the date is in the 21st century.

答案

public class SmartDate2 {

    @SuppressWarnings("unused")
    private final int year;
    @SuppressWarnings("unused")
    private final int month;
    @SuppressWarnings("unused")
    private final int day;
    
    private static final int YEARFIRSTTWO = 20;
    private static final int DAYPERWEEK = 7;

    public SmartDate2(int year, int month, int day) throws Exception {
        if (year < 0 || month < 0 || day < 0) {
            Exception exception = new Exception("年月日要大于0");
            throw exception;
        }
        if (month > 12) {
            Exception exception = new Exception("年份要小于等于12");
            throw exception;
        }

        switch (month) {
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
        case 1: {
            if (day > 31) {
                Exception exception = new Exception(month + "月小于31号");
                throw exception;
            }
        }
            break;
        case 2: {
            if (day > 29) {
                Exception exception = new Exception(month + "月小于31号");
                throw exception;
            }

            int leapYear = year % 4;
            if (leapYear != 0) {
                if (day > 28) {
                    Exception exception = new Exception(month + "月小于29号");
                    throw exception;
                }
            }

        }
            break;
        case 4:
        case 6:
        case 9:
        case 11: {
            if (day > 30) {
                Exception exception = new Exception(month + "月小于30号");
                throw exception;
            }
        }
            break;

        default:
            break;
        }

        this.day = day;
        this.year = year;
        this.month = month;
    }
    
    public String dayOfTheWeek(){
        String resultWeek = "";
        int tempMonth = this.month;
        int tempYear = this.year;
        int tempDay = this.day;
        if (this.month == 1 || this.month == 2) {
            tempMonth += 12;
            tempYear --;
        }
        
        int y = tempYear - YEARFIRSTTWO * 100;
        int floor1 = (int) Math.floor(y/4);
        int floor2 = (int) (YEARFIRSTTWO / 4);
        int floor3 = (int) Math.floor(26 * (tempMonth+1)/10);
        
        int w = y + floor1 + floor2 -2 * YEARFIRSTTWO + floor3 + tempDay - 1;
        int key = w % DAYPERWEEK;
        
        if (key <0) {
            key = key + 7;
        }
        
        
        switch (key) {
        case 0:
            resultWeek = "星期日";
            break;
        case 1:
            resultWeek = "星期一";
            break;
        case 2:
            resultWeek = "星期二";
            break;
        case 3:
            resultWeek = "星期三";
            break;
        case 4:
            resultWeek = "星期四";
            break;
        case 5:
            resultWeek = "星期五";
            break;
        case 6:
            resultWeek = "星期六";
            break;

        default:
            break;
        }
        
        return resultWeek;
    }
    
    public String toString(){
        
        return ""+ month + "/" + day + "/" + year;
    }

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        SmartDate2 date = new SmartDate2(2012, 2, 28);
        String week = date.dayOfTheWeek();
        System.out.println( date + " is :" + week);
    }

}

代码索引

SmartDate2.java

视频讲解

点此观看分析视频

注意

这里的SmartDate1,SmartDate2,实现还不够完善,会在下一篇文章
算法练习(25):Transaction(1.2.13-1.2.14)中进行更改。

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