我必须分割用户以DDMMYYYY格式输入的日期。但是，如果您输入70702000，它显示的是我的所有3个错误，而不是一个

Question

    {
        System.out.println("Please enter the date you would like to split");
        System.out.println("Please make sure it is in the format DDMMYYYY");
        date = sc.nextInt();

        day = date / 1000000;
        month = (date / 10000) - (day * 100);
        year = date - (date / 10000) * (10000);

        switch(day) 
        {
            case 1: case 21: case 31: 
                suffix = "st";
            break;

            case 2: case 22:
                suffix = "nd";
            break;

            case 3: case 23: 
                suffix = "rd";
            break;

            case 4: case 5: case 6: case 7: case 8: case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: case 17: case 18: case 19: case 20: case 24: case 25: case 26: case 27: case 28: case 29: case 30:
                suffix = "th";
            break;

            default:
                System.out.println("Error, Please enter a valid day (i.e. DD) that is between 01 - 31");
            break;
        }

        switch(month)
        {
            case 4: case 6: case 9: case 11: 
                if ((day < 1) || (day > 30))
                {
                    System.out.println("Error this day does not exist"); 
                }
            break;

            case 1: case 3: case 5: case 7: case 8: case 10: case 12: 
                if ((day < 1) || (day > 31))
                {
                    System.out.println("Error this day does not exist");
                }
            break;

            case 2:
                if ((day < 1) || (day > 28))
                {
                    if ((day != 29)) 
                    {
                        System.out.println("Error this day does not exist");
                    }
                    else if ((year % 4 != 0) || ((year % 400 != 0) && (year % 100 == 0)))
                    {
                        System.out.println("Error this day does not exist");
                    }
                        //If it isn't a leap year, febuary cannot have 29 days
                }
            break;
            default:
                System.out.println("Error this day does not exist");
        }

        switch(month)
        {
            case 1:
                monthName = "January";
            break;
            case 2:
                monthName = "Febuary";
            break;
            case 3: 
                monthName = "March";
            break;
            case 4:
                monthName = "April";
            break;
            case 5: 
                monthName = "May";
            break; 
            case 6: 
                monthName = "June";
            break;
            case 7:
                monthName = "July";
            break;
            case 8:
                monthName = "August";
            break;
            case 9: 
                monthName = "September";
            break; 
            case 10:
                monthName = "October";
            break;
            case 11: 
                monthName = "November";
            break;
            case 12:
                monthName = "December";
            default:
                System.out.println("Error, Please make sure the month (i.e. MM) is between 01 and 12");
            break;
        }

        if ((day == 29) && (month == 2))
        {
            System.out.println("It is the 29th day of Febuary in " + year + ".");
        }
        else 
        {
            System.out.println("It is the " + day + suffix + " day of " + monthName + " in " + year + ".");
        }
    }

所以基本上，当我运行此程序并输入70702020时，我将获得所有这些输出“错误，请输入介于01-31之间的有效日期（即DD）”“今天没有错误”“错误，请确保月份（即MM）在01到12之间”然后它将输出最终输出（仅当用户输入有效日期时才打算使用此输出）

Answer 1

您正在使用开关而不是if（blah blah）语句。意思是说，该陈述是正确的，现在会产生错误。您的代码说您的输入没有问题。您的后缀仍然会打印，但是我会打印空引号，因为它是一个空字符串。我建议在使用开关之前检查输入。或使用“ System.exit（1）”，如果输入错误，系统将退出该系统。

编辑：同样，根据您的计算，您的工作日将等于“ 70”，从而导致其他错误。

Answer 2

[break仅打破switch语句

switch语句中的break命令只能从switch语句中退出，不是整个方法。

您有一系列三个switch语句。

• 当您跳出第一条switch语句时，控制流将移至第二条switch语句。
• 当您脱离第二个switch语句时，控制流程将移至第三个switch语句。
• 当您跳出第三条switch语句时，控制流将移至其余语句。

java.time

顺便说一句，通过现代的java.time类解析为文本要简单得多。

try {
    LocalDate ld = 
            LocalDate
            .parse( 
                "70702020" , 
                DateTimeFormatter.ofPattern( "ddMMuuuu" ) 
            )
    ;
} catch ( DateTimeParseException e ) {
    … 
}

无效的输入抛出DateTimeParseException。

Answer 3

我建议看一下注释，然后自己执行代码。我添加一些评论。