带有return语句的Java开关

Question

我需要返回用户从命令行输入的数字的值。

例如：

java Test 5 

1 =一月

2 =二月，等等...

我尝试使用switch语句，但是，我收到输出：

May
5

当从命令行输入时。我不确定为什么会这样。

输出应为：

/May

这是到目前为止我尝试过的：

class theDate {

private int month;


public theDate(int theMonth){

    month = theMonth;

}

public theDate(){

}

public int getMonth() {

    switch (month) {

      case 1: System.out.println("January"); break;

      case 2: System.out.println("February"); break;

      case 3: System.out.println("March"); break;

      case 4: System.out.println("April"); break;

      case 5: System.out.println("May"); break;

      case 6: System.out.println("June"); break;

      case 7: System.out.println("July"); break;

      case 8: System.out.println("August"); break;

      case 9: System.out.println("September"); break;

      case 10: System.out.println("October"); break;

      case 11: System.out.println("November"); break;

      case 12: System.out.println("December"); break;



        }

        return month;

}



public String getDate(String[] datePartsObj) {


        month = Integer.parseInt(datePartsObj[0]);


        return "/" + month;

    }

}


public class Test {

private MyDate myDateObj;


public Test(){

}


public static void main(String [] args) {

    String[] datePartsObj;
    datePartsObj = args[0].split("/");
    int month = Integer.parseInt(datePartsObj[0]);

    theDate myDateObj = new theDate(month);

    System.out.println(myDateObj.getMonth());

    }

}

我对Java还是很陌生，因此不胜感激！

Answer 1

好像您想通过检查给定的数字来返回月份名称。

您必须更改返回String而不是int的方法，然后可以直接在匹配的case中返回名称，如下所示：

public String getMonth() {
    switch (month) {
    case 1:
        // print the name of the month
        System.out.println("January");
        // and return it... same for ever other month
        return "January";
    case 2:
        System.out.println("February");
        return "February";
    case 3:
        System.out.println("March");
        return "March";
    case 4:
        System.out.println("April");
        return "April";
    case 5:
        System.out.println("May");
        return "May";
    case 6:
        System.out.println("June");
        return "June";
    case 7:
        System.out.println("July");
        return "July";
    case 8:
        System.out.println("August");
        return "August";
    case 9:
        System.out.println("September");
        return "September";
    case 10:
        System.out.println("October");
        return "October";
    case 11:
        System.out.println("November");
        return "November";
    case 12:
        System.out.println("December");
        return "December";
    // for any number less than 1 and greater than 12 throw an exception
    default:
        throw new RuntimeException("Invalid month number");
    }
}

Answer 2

您的整个工作流程都有2条打印语句要执行。一种在getMonth()方法内（正在打印“ MAY”），另一种在main()方法内（正在打印5）

您需要做的是将getMonth()的返回类型从int更改为String

 public String getMonth() {

    switch (month) {

      case 1: return "January";

      case 2: return "February";

      case 3: return "March";

      case 4: return "April";

      case 5: return "May";

      case 6: return "June";

      case 7: return "July";

      case 8: return "August";

      case 9: return "September";

      case 10: return "October";

      case 11: return "November";

      case 12: return "December";

        }

        return "Invalid Month";

}

这样，您的工作流程将在main方法中只有一个打印语句。