我怎样才能简化我的代码？

Question

我最近写了一个程序来计算 1900 年之后的第 13 个星期五。代码非常好并且可以工作；但是有些部分非常多余。反正有没有我可以简化它。

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class friday {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("friday.in"));
        PrintWriter pw= new PrintWriter(new FileWriter("friday.out"));
        int years = Integer.parseInt(br.readLine());
        int saturday = 0;
        int sunday = 0;
        int monday = 0;
        int tuesday = 0;
        int wedensday = 0;
        int thursday = 0;
        int friday = 0;
        int month = 1;
        int day = 1;
        int months = 12*years;
        int test = 0;
        int year = 1900;

        for(int i = 0; i < months; i++)
        {
            if ((year % 4 == 0) && year % 100 != 0)
            {
                test = 1;
            }
            else if ((year % 4 == 0) && (year % 100 == 0) && (year % 400 == 0))
            {
                test = 1;
            }
            else
            {
                test = 0;
            }

        if(month == 1)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 2)
        {
            if(test == 1)
            {
                if(day == 1)
                {
                    saturday++;
                }
                if(day == 2)
                {
                    sunday++;
                }
                if(day == 3)
                {
                    monday++;
                }
                if(day == 4)
                {
                    tuesday++;
                }
                if(day == 5)
                {
                    wedensday++;
                }
                if(day == 6)
                {
                    thursday++;
                }
                if(day == 0)
                {
                    friday++;
                }
                //leapyear = 1;
                day = (day + 1) % 7;
            }
            else
            {
                if(day == 1)
                {
                    saturday++;
                }
                if(day == 2)
                {
                    sunday++;
                }
                if(day == 3)
                {
                    monday++;
                }
                if(day == 4)
                {
                    tuesday++;
                }
                if(day == 5)
                {
                    wedensday++;
                }
                if(day == 6)
                {
                    thursday++;
                }
                if(day == 0)
                {
                    friday++;
                }
                day = (day + 0) % 7;
                //leapyear++;
            }
        }
        if(month == 3)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 4)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 2) % 7;
        }
        if(month == 5)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 6)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 2) % 7;
        }
        if(month == 7)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 8)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 9)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 2) % 7;
        }
        if(month == 10)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
        }
        if(month == 11)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 2) % 7;
        }
        if(month == 0)
        {
            if(day == 1)
            {
                saturday++;
            }
            if(day == 2)
            {
                sunday++;
            }
            if(day == 3)
            {
                monday++;
            }
            if(day == 4)
            {
                tuesday++;
            }
            if(day == 5)
            {
                wedensday++;
            }
            if(day == 6)
            {
                thursday++;
            }
            if(day == 0)
            {
                friday++;
            }
            day = (day + 3) % 7;
            year++;
        }

        month = (month + 1) % 12;


    }
        pw.println(saturday + " " + sunday + " " + monday + " " + tuesday + " " + wedensday+ " " + thursday + " " + friday);
        pw.close();
        //System.out.println(saturday + " " + sunday + " " + monday + " " + tuesday + " " + wedensday+ " " + thursday + " " + friday);
    }
}

Answer 1

好吧，一方面，您的代码没有达到您声明的目标。无论如何，简短的回答是使用 Calendar 对象。

如果你只想像你说的那样计算 13 号星期五的数量，这里是代码：

public static int countFriday13(int years) {
    Calendar cal = Calendar.getInstance();
    cal.clear();
    cal.set(1900, Calendar.JANUARY, 13);
    int count = 0;
    for (int i = 0; i < years * 12; i++) {
        if (cal.get(Calendar.DAY_OF_WEEK) == Calendar.FRIDAY)
            count++;
        cal.add(Calendar.MONTH, 1);
    }
    return count;
}

Answer 2

大大改进代码的最简单方法是使用数组。此外，您必须了解 if 语句的逻辑才能压缩它们。为了可读性，当你想说days in a week时不要使用7，当你想说years in a month时不要使用12。 创建具有明确名称的常量并在任何需要的地方使用它们。

下面是您重构第一步的开始。检查这个简化的代码是否仍然有效，并用它来进一步改进它（更好的名字，更明确的逻辑 incrementForMonth...）。

public class friday {
    private static final int DAYS_IN_WEEK = 7;
    private static final int MONTHS_IN_YEAR = 12;

    private static void updateDays(int[] days, int day) {
        checkIsInRange(0, year, DAYS_IN_WEEK);
        days[(day + 4) % DAYS_IN_WEEK]++;
    }

    private static boolean isLeapYear(int year) {
       checkIsInRange(0, year, MONTHS_IN_YEAR);
       return (year % 4 == 0) && (year % 100 != 0 || year % 400 == 0);
    }

    private static void checkIsInRange(int inclusiveLowerBound, int toTest, int exclusiveUpperBound) {
         if (toTest < inclusiveLowerBound || exclusiveUpperBound <= toTest) throw new IllegalArgumentException(toTest + " not in [" + inclusiveLowerBound + ", " + exclusiveUpperBound + "]");                 
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("friday.in"));
        PrintWriter pw= new PrintWriter(new FileWriter("friday.out"));
        int years = Integer.parseInt(br.readLine());

        int month = 1;
        int day = 1;
        int months = MONTHS_IN_YEAR*years;
        int test = 0;
        int year = 1900;

        int days = int[DAYS_IN_WEEK];
        int[] incrementForMonth = { 3, 3, 1, 3, 2, 3, 2, 3, 3, 2, 3, 2 }; 

        for(int i = 0; i < months; i++) {
            test = isLeapYear(year) ? 1 : 0;

            updateDays(days, day);
            if (month != 2 || test == 1) {
                day = (day + incrementForMonth[month]) % DAYS_IN_WEEK;
            }
            if (month == 0) {
                year++;
            }
        }

        month = (month + 1) % MONTHS_IN_YEAR;
    }
    pw.println(saturday + " " + sunday + " " + monday + " " + tuesday + " " + wedensday+ " " + thursday + " " + friday);
    pw.close();
}

我怎样才能简化我的代码？

How can I simplify my code?

java

algorithm

simplify