如何获取一个月的输入以匹配案例#答案

【问题标题】：How to get the input of a month to match with a case #如何获取一个月的输入以匹配案例#
【发布时间】：2017-05-23 17:42:17
【问题描述】：

我不知道如何获取月份的输入以匹配 case #。我有点知道该怎么做，但不确定要在我的代码中添加什么才能使其正常工作。

这是作业：

编写一个程序，提示用户输入月份名称，然后使用开关显示季节名称。假设春季月份是三月、四月和五月；夏季是六月、七月、八月；秋天是九月、十月、十一月；冬天是十二月，一月，二月。您必须使用开关。对于完整点，您的开关代码应该证明语句的经济性，并且它应该以错误消息响应错误输入

这是我目前所拥有的：

import java.util.Scanner;
public class Assignment4 {
    private static Scanner input;
    public static void main(String[] args) {
        input = new Scanner(System.in);
        System.out.println("Enter the name of a month");
        int month = input.nextInt();
        switch (month) {
          case 12: season = "winter"; break;
          case 1: season = "winter"; break;
          case 2: season = "winter"; break;
          case 3: season = "spring"; break;
          case 4: season = "spring"; break;
          case 5: season = "spring"; break;
          case 6: season = "summer"; break;
          case 7: season = "summer"; break;
          case 8: season = "summer"; break;
          case 9: season = "fall"; break;
          case 10: season = "fall"; break;
          case 11: season = "fall"; break;
          default: System.out.println("Error: invalid month.");
}
        System.out.println("The season of the month " + month + "is " + season + ".");
}}

【问题讨论】：

...什么不起作用？请修正你的缩进。
Enter the name，但您正在检查月份数！
为了更经济的语句，您可以对 case 语句使用 fallthrough - 尽管这在专业代码中不是一件好事（容易出错，因为您也可能忘记了 break 语句）：@ 987654323@

标签： java switch-statement java.util.scanner

【解决方案1】：

你快到了，有两个提示可以让你走得更远：

编写一个程序，提示用户输入月份名称，然后使用开关显示

所以使用：

String month = scanner.next();

请求一个字符串；然后切换：

case "december" : ...

就是这样！

此外，您可能需要在传入字符串上调用trim()；并且您还想使用toLowerCase() 来确保您不会遇到“十二月”与“十二月”不同的情况。

【讨论】：

对不起，我还是新手，我该把 String、trim() 和 toLowerCase() 放在哪里
在输入被收集到一个变量（在本例中为字符串月份）之后和 switch 语句之前。您基本上是将输入清理为标准化格式。所以很自然，您会希望在获得输入之后但在使用输入之前执行此操作。
@michael 您可以链接函数并执行String month = scanner.next().trim().toLowerCase();，也可以在String month = scanner.next(); 之后添加单独的语句，例如month = month.trim();。
@michael 我故意省略了这些细节。这是你的作业。只是谷歌的话，例如“java string trim”。向其他人解释所有细节时，您不会学到很多东西。

【解决方案2】：

为了节省代码语句，您可以同时使用多个大小写。

接受输入

String month = input.nextLine().trim().toLowerCase();

开关盒

switch (month) {
        case "march":
        case "april":
        case "may":
            season = "spring";
            break;
        case "june":
        case "july":
        case "august":
            season = "summer";
            break;

按照@GhostCat 的建议添加了修剪和小写

【讨论】：

但这总是将月份打印为小写字母！
我其实是建议让他自己发现的 ;-)

【解决方案3】：

您应该能够对字符串进行切换，但如果您想保留此代码，您需要一个函数，该函数将接受像“June”这样的字符串并返回 6 或“January”返回 12。

【讨论】：

【解决方案4】：

**你还没有在课堂上声明赛季试试这个它工作**

public class Assignment4 {
private static Scanner input;
public static void main(String[] args) {
    input = new Scanner(System.in);
    String season=null;
    System.out.println("Enter the name of a month");
    int month = input.nextInt();
    switch (month) {
      case 12: season = "winter"; break;
      case 1: season = "winter"; break;
      case 2: season = "winter"; break;
      case 3: season = "spring"; break;
      case 4: season = "spring"; break;
      case 5: season = "spring"; break;
      case 6: season = "summer"; break;
      case 7: season = "summer"; break;
      case 8: season = "summer"; break;
      case 9: season = "fall"; break;
      case 10: season = "fall"; break;
      case 11: season = "fall"; break;
      default: System.out.println("Error: invalid month.");

}   

         System.out.println("The season of the month " + month + "is " + season + ".");
    }}

为此

【讨论】：

【解决方案5】：

你可以这样做：

Scanner input = new Scanner(System.in);
System.out.println("Enter the month:");
try{ // wrap with try-catch block in case user entered invalid input (not a number)
    int month = Integer.parseInt(input.nextLine()); // it's better to read the entire line then parse it

    // use the ternary condition and one String variable
    String result = (month==1||month==2||month==12)  ? "The season of the month " + month + " is Winter."  :
                    (month==3||month==4||month==5)   ? "The season of the month " + month + " is Spring."  :
                    (month==6||month==7||month==8)   ? "The season of the month " + month + " is Summber." :
                    (month==9||month==10||month==11) ? "The season of the month " + month + " is Fall."    : "Error: invalid month.";

    System.out.println(result); // print out the result

   }catch(NumberFormatException e){ // if your program reaches this point that means it's not a number
        System.out.println("Error: invalid Input, Please use number only.");
   }

测试

Enter the month:
Text  ->  Error: invalid Input, Please use number only.
1     ->  The season of the month 1 is Winter.
5     ->  The season of the month 5 is Spring.
13    ->  Error: invalid month.

更新：

如果您被要求使用switch 作为强制性要求，您可以这样做：

Scanner input = new Scanner(System.in);
System.out.println("Enter the name of a month:");

String month = input.nextLine().trim(); // read the entire line and remove leading spaces by using trim() method


String result;
switch(month.toLowerCase()){
    case "january": case "february": case "december":
        result = "The season of the month " + month + " is Winter.";
    break;

    case "march": case "april": case "may":
        result = "The season of the month " + month + " is Spring.";
    break;

    case "jun": case "july": case "august":
        result = "The season of the month " + month + " is Summber.";
    break;

    case "september": case "october": case "november":
        result = "The season of the month " + month + " is Fall.";
    break;

    default: 
        result = "Error: invalid month.";
}


 System.out.println(result); // print out the result

测试

Enter the name of a month:
January     ->  The season of the month January is Winter.
APRIL       ->  The season of the month APRIL is Spring.    
Not a month ->  Error: invalid month.

【讨论】：