对一个switch case语句使用两个值 [英] Using two values for one switch case statement

问题描述

在我的代码中，程序会根据用户输入的文本执行某些操作。我的代码如下：

In my code, the program does something depending on the text entered by the user. My code looks like:

switch (name) {
        case text1: {
            //blah
            break;
        }
        case text2: {
            //blah
            break;
        }
        case text3: {
            //blah
            break;
        }
        case text4: {
            //blah
            break;
        }

然而，案例中的代码 text1 和 text4 是一样的。因此，我想知道是否有可能实现类似

However, the code inside cases text1 and text4 is the same. I was therefore wondering if it would be possible for me to implement something like

case text1||text4: {
            //blah
            break;
        }

我知道 || 运算符在case语句中不起作用，但是我可以使用类似的东西。

I know that the || operator won't work in the case statement but is there something similar I can use.

推荐答案

你可以使用have两个 CASE 语句如下。

You can use have both CASE statements as follows.

  case text1: 
  case text4:{
            //blah
            break;
        }

查看此示例：代码示例计算特定月份的天数：

SEE THIS EXAMPLE:The code example calculates the number of days in a particular month:

class SwitchDemo {
    public static void main(String[] args) {

        int month = 2;
        int year = 2000;
        int numDays = 0;

        switch (month) {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                numDays = 31;
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                numDays = 30;
                break;
            case 2:
                if (((year % 4 == 0) && 
                     !(year % 100 == 0))
                     || (year % 400 == 0))
                    numDays = 29;
                else
                    numDays = 28;
                break;
            default:
                System.out.println("Invalid month.");
                break;
        }
        System.out.println("Number of Days = "
                           + numDays);
    }
}

这是代码的输出：

Number of Days = 29

FALLTHROUGH：

FALLTHROUGH:

另一个兴趣点是break语句。每个break语句
终止封闭的switch语句。控制流继续以
继续切换块之后的第一个语句。 break语句
是必需的，因为如果没有它们，switch块中的语句将通过降低
：匹配的case标签之后的所有语句都以$ b $执行b序列，无论后续案例标签的表达如何，
直到遇到break语句。

Another point of interest is the break statement. Each break statement terminates the enclosing switch statement. Control flow continues with the first statement following the switch block. The break statements are necessary because without them, statements in switch blocks fall through: All statements after the matching case label are executed in sequence, regardless of the expression of subsequent case labels, until a break statement is encountered.

示例代码：

public class SwitchFallThrough {

    public static void main(String[] args) {
        java.util.ArrayList<String> futureMonths =
            new java.util.ArrayList<String>();

        int month = 8;

        switch (month) {
            case 1:  futureMonths.add("January");
            case 2:  futureMonths.add("February");
            case 3:  futureMonths.add("March");
            case 4:  futureMonths.add("April");
            case 5:  futureMonths.add("May");
            case 6:  futureMonths.add("June");
            case 7:  futureMonths.add("July");
            case 8:  futureMonths.add("August");
            case 9:  futureMonths.add("September");
            case 10: futureMonths.add("October");
            case 11: futureMonths.add("November");
            case 12: futureMonths.add("December");
            default: break;
        }

        if (futureMonths.isEmpty()) {
            System.out.println("Invalid month number");
        } else {
            for (String monthName : futureMonths) {
               System.out.println(monthName);
            }
        }
    }
}

这个是代码的输出：

August
September
October
November
December

在交换机语句中使用字符串

Using Strings in switch Statements

在Java SE 7及更高版本中，您可以在switch
语句的表达式中使用String对象。下面的代码示例，
显示基于String
命名月份的值的月份编号：

In Java SE 7 and later, you can use a String object in the switch statement's expression. The following code example, , displays the number of the month based on the value of the String named month:

public class StringSwitchDemo {

    public static int getMonthNumber(String month) {

        int monthNumber = 0;

        if (month == null) {
            return monthNumber;
        }

        switch (month.toLowerCase()) {
            case "january":
                monthNumber = 1;
                break;
            case "february":
                monthNumber = 2;
                break;
            case "march":
                monthNumber = 3;
                break;
            case "april":
                monthNumber = 4;
                break;
            case "may":
                monthNumber = 5;
                break;
            case "june":
                monthNumber = 6;
                break;
            case "july":
                monthNumber = 7;
                break;
            case "august":
                monthNumber = 8;
                break;
            case "september":
                monthNumber = 9;
                break;
            case "october":
                monthNumber = 10;
                break;
            case "november":
                monthNumber = 11;
                break;
            case "december":
                monthNumber = 12;
                break;
            default: 
                monthNumber = 0;
                break;
        }

        return monthNumber;
    }

    public static void main(String[] args) {

        String month = "August";

        int returnedMonthNumber =
            StringSwitchDemo.getMonthNumber(month);

        if (returnedMonthNumber == 0) {
            System.out.println("Invalid month");
        } else {
            System.out.println(returnedMonthNumber);
        }
    }
}

此代码的输出是8。

FROM Java Docs

这篇关于对一个switch case语句使用两个值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！