一周中的日子

Question

我正在尝试制作一个程序，从用户输入中获取日期，然后告诉他们前一天和那天 after.The 用户还应该能够输入要添加的天数和程序那天应该输出。

示例用户输入 1 = 星期一，明天 = 2 星期二昨天 = 3 星期日

如果用户说是星期一 (1) 并加上 12 天，则输出应该是星期六 (6)

问题是每当 "theWeekDay" 大于 7 时它什么都不输出，因为 TheDay();没有大于 7 的条件。请帮助我！

非常感谢！

import java.util.Scanner;
import java.util.Scanner;

public class Problem_3 {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        int theWeekDay;
        System.out.println("What Day Is It?");
        theWeekDay = input.nextInt();
        Days one = new Days(theWeekDay);
        System.out.println("Today It Is: ");
        one.TheDay(theWeekDay);
        System.out.println("Yesterday It Was: ");
        one.PreviousDay(theWeekDay);
        System.out.println("Tomorrow It Is: ");
        one.NextDay(theWeekDay);
        System.out.println("How Many Days To Add?");
        int x = input.nextInt();
        System.out.println("Now It Is: ");
        one.AddedDays(x);
    }
}

class Days {
    private int theWeekDay;

    public Days(int theWeekDay) {
        this.theWeekDay = theWeekDay;
    }

    public int getTheWeekDay() {
        return theWeekDay;
    }

    public void setTheWeekDay(int theWeekDay) {
        this.theWeekDay = theWeekDay;
    }

    public int TheDay(int theWeekDay) {
        // an arra days of week + then add days in it
        if (theWeekDay == 0) {
            theWeekDay = theWeekDay + 7;
        }

        if (theWeekDay == 1) {
            System.out.println("Monday");
        } else if (theWeekDay == 2) {
            System.out.println("Tuesday");
        } else if (theWeekDay == 3) {
            System.out.println("Wednsday");
        } else if (theWeekDay == 4) {
            System.out.println("Thursday");
        } else if (theWeekDay == 5) {
            System.out.println("Friday");
        } else if (theWeekDay == 6) {
            System.out.println("Saturday");
        } else if (theWeekDay == 7) {
            System.out.println("Sunday");
        }
        return theWeekDay;
    }

    public int PreviousDay(int theWeekDay) {
        theWeekDay = theWeekDay - 1;
        return TheDay(theWeekDay);
    }

    public int NextDay(int theWeekDay) {
        theWeekDay = theWeekDay + 1;
        if (theWeekDay > 7) {
            theWeekDay = 1;
        }
        return TheDay(theWeekDay);
    }

    public int AddedDays(int AddedDays) {
        getTheWeekDay();
        theWeekDay = theWeekDay + AddedDays;
        return TheDay(theWeekDay);
    }
}

Answer 1

您的 if else 必须涵盖所有情况....

在

之后添加一个else

else if(theWeekDay == 7){
        System.out.println("Sunday");
    }

类似于：

if(theWeekDay == 1){
    System.out.println("Monday");
}else if(theWeekDay == 2){
    System.out.println("Tuesday");
}else if(theWeekDay == 3){
    System.out.println("Wednsday");
}else if(theWeekDay == 4){
    System.out.println("Thursday");
}else if(theWeekDay == 5){
    System.out.println("Friday");
}else if(theWeekDay == 6){
    System.out.println("Saturday");
}else if(theWeekDay == 7){
    System.out.println("Sunday");
}else{
    System.out.println("Invalid input");
}
return theWeekDay;

Answer 2

如果您想假设大于 7 的值有效，您一定要使用模运算。像这样：

if(theWeekDay > 7) {
    theWeekDay = theWeekDay % 7;
}

否则你应该抛出异常。

Answer 3

正如 user629735 所说，在你的公式中使用模数。

public int AddedDays(int AddedDays) {
    getTheWeekDay();
    theWeekDay = (theWeekDay + AddedDays) % 7;
    return TheDay(theWeekDay);
}

一周中的日子

Days of the week

java

class

dayofweek