有没有办法将用户输入的字符串分配给一个 int 值？

Question

`我还在学习，我觉得我做这一切都是错的，但我需要一些帮助。我有一个任务需要让用户设置一周中的某一天，然后程序会让用户选择一个选项，返回当天、返回第二天、返回前一天，或者将某些天添加到这一天他们设置（例如：如果将日期设置为星期一并添加 4 天，则它将返回星期五）。我真的只需要添加天数部分的帮助，但任何关于如何使代码更好的建议都值得赞赏。

---

我想知道我是否可以将一个 int 值分配给一个字符串。例如，如果 String day 等于“Sunday”，则 int a = 1。我想将一周中的每一天分配给一个 int 值，然后将用户输入的任何数字添加到 int 值，然后总和将是新的天。

---

如果有更好的方法来做到这一点，请告诉我，这是我的代码（抱歉，如果它看起来不好）。

import java.util.Scanner;
public class Main
{
public static void main(String\[\] args)
{

        Day.userInput();
    }

}

class Day
{
static int b;
public static void userInput()
{
Scanner scan = new Scanner(System.in);

// set day of week
System.out.println("Please set the day of the week:");
String day = scan.nextLine();

        if(day.equals("sunday") || (day.equals("Sunday")) )
        {
          b = 1;
        }
        if(day.equals("monday") || (day.equals("Monday")) )
        {
            b = 2;
        }
        if(day.equals("tuesday") || (day.equals("Tuesday")) )
        {
            b = 3;
        }
        if(day.equals("wednesday") || (day.equals("Wednesday")) )
        {
            b = 4;
        }
        if(day.equals("thursday") || (day.equals("Thursday")) )
        {
            b = 5;
        }
        if(day.equals("friday") || (day.equals("Friday")) )
        {
            b = 6;
        }
        if(day.equals("saturday") || (day.equals("Saturday")) )
        {
            b = 7;
        }
    
    
        System.out.println("Enter 1 to return the day.\nEnter 2 to return tomorrows day.\nEnter 3 to return yesterdays day.\nEnter 4 to add days to the current day.\n");
        int a = scan.nextInt();

// return day
if(a == 1)
{
System.out.println("The day is " + day);
}
//return next day
if(a == 2)
{
if ( b == 1)
{
System.out.println("The next day is Monday.");
}
if (b == 2)
{
System.out.println("The next day is Tuesday.");
}
if (b == 3)
{
System.out.println("The next day is Wednesday.");
}
if (b == 4)
{
System.out.println("The next day is Thursday.");
}
if (b == 5)
{
System.out.println("The next day is Friday.");
}
if (b == 6)
{
System.out.println("The next day is Saturday.");
}
if (b == 7)
{
System.out.println("The next day is Sunday.");
}

        }

//return previous day
if(a == 3)
{
if( b == 1)
{
System.out.println("The previous day was Saturday.");
}
if (b == 2)
{
System.out.println("The previous day was Sunday.");
}
if (b == 3)
{
System.out.println("The previous day was Monday.");
}
if (b == 4)
{
System.out.println("The previous day was Tuesday.");
}
if (b == 5)
{
System.out.println("The previous day was Wednesday.");
}
if (b == 6)
{
System.out.println("The previous day was Thursday.");
}
if (b == 7)
{
System.out.println("The previous day was Friday.");
}
}
// add days  
if(a == 4 )
{
System.out.println("Enter the number of days you want to add");
int c = scan.nextInt();

        }
    
    
    }

}

我知道我可以做到这一点的方法，但它需要大量的行和 if 语句。 `

Answer 1

您可以按顺序创建List，然后将输入的String转换为小写后使用indexOf。

List<String> days = List.of("sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday");
// convert day to index:
int b = days.indexOf(day.toLowerCase()) + 1;

// convert index to day:
String day = days.get(a - 1);
// capitalize it:
day = Character.toUpperCase(day.charAt(0)) + day.substring(1);

Answer 2

虽然上面的答案清晰准确，但您也可以使用包含一周中所有日期的 enum，主要是为了防止您还想向它们添加更多功能。

enum DayOfWeek {
    MONDAY(1), TUESDAY(2), WEDNESDAY(3), THURSDAY(4), FRIDAY(5), SATURDAY(6), SUNDAY(7);

    private final int value;

    private DayOfWeek(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }

    public DayOfWeek getPreviousDay() {
        if (value == 1) return DayOfWeek.SUNDAY;
        if (value == 2) return DayOfWeek.MONDAY;
        // Insert other checks here
    }

    public DayOfWeek getNextDay() {
        if (value == 7) return DayOfWeek.MONDAY;
        // Insert other checks here
    }
}

... 而用户输入部分可能如下所示：

Scanner scan = new Scanner(System.in);

System.out.println("Please set the day of the week:");
String day = scan.nextLine();

DayOfWeek dayOfWeek = DayOfWeek.valueOf(day);

当然，在这种情况下，如果用户输入了正确的值，但大小写错误（例如mondaY或Monday），它会抛出一个Exception。用户应输出MONDAY，如DayOfWeek中所指定。您只需添加以下内容即可轻松将 day 转换为大写：

DayOfWeek dayOfWeek = DayOfWeek.valueOf(day.toUpperCase());