执行 do while 和 exit

Question

作为 Java 的新手，我编写了这个程序来计算各种货币。我想询问用户是否希望重复该过程，直到用户希望退出。请协助我解决这个问题。到目前为止我的代码：

public static void main(String[] args) {


    Scanner input = new Scanner(System.in); 
    DecimalFormat formatter = new DecimalFormat("#0.00");

    String CType, c1 = "US", c2 = "EUR", c3 = "RM", c4 = "SAR"; 
    double CValue , US, EUR, RM, SGD, SAR;


    System.out.println("Welcome to Bonus Calculator");

    System.out.println("Enter any of the following Currencies:"); 
    System.out.print("US\n" +
                     "EUR\n" +
                     "RM\n" +
                     "SGD\n" +
                     "SAR: ");
    CType = input.next();



   if(CType.equalsIgnoreCase("US")){
     System.out.print("Enter Value: ");
     CValue = input.nextInt();

       EUR = CValue * .88;
       RM = CValue * 3.92;
       SGD = CValue * 1.35;
       SAR = CValue * 3.75;

   System.out.print("US = " + formatter.format(CValue) + "EUR =" + formatter.format(EUR) + "RM =" + formatter.format(RM) + "SGD =" + formatter.format(SGD) + "SAR =" + formatter.format(SAR));

   }

   else if(CType.equalsIgnoreCase("EU")){ 
       System.out.print("Enter Value: ");
       CValue = input.nextInt();
       US = CValue * 1.14;
       RM = US * 3.92;
       SGD = US * 1.35;
       SAR = US * 3.75;

   System.out.print("EUR = " + formatter.format(CValue) + " US = " + formatter.format(US) + " RM = " + formatter.format(RM) +" SGD = " + formatter.format(SGD) +" SAR = " + formatter.format(SAR));

   }

   else if (CType.equalsIgnoreCase("RM")){
       System.out.print("Enter Value: ");
       CValue = input.nextInt();
       US = CValue * .26;
       EUR = US * .88;
       SGD = US * 1.35;
       SAR = US * 3.75;

   System.out.print("RM = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SGD = " + formatter.format(SGD) + " SAR = " + formatter.format(SAR));

   }

   else if (CType.equalsIgnoreCase("SGD")){
       System.out.print("Enter Value: ");
       CValue = input.nextInt();
       US = CValue * 0.74;
       EUR = US * .88;
       RM = US * 3.92;
       SAR = US * 3.75;

   System.out.print("SGD = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SAR = " + formatter.format(SAR) + " RM = " + formatter.format(RM));

   }

   else if(CType.equalsIgnoreCase("SAR")){
       System.out.print("Enter Value: ");
       CValue = input.nextInt();
       US = CValue * 0.39;
       EUR = US * .88;
       RM = US * 3.92;
       SGD = US * 1.35;

   System.out.print("SAR = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SGD = " + formatter.format(SGD) + " RM = " + formatter.format(RM));

   }

}

Answer 1

将所有代码包装在一个循环中，并使用像 keepRunning 这样初始化为 true 的布尔变量。在循环结束时，您询问用户（从扫描仪获取输入），然后检查输入的意思是 "yes" 还是 "no"（或者换句话说是真还是假）并设置 keepRunning 因此（这意味着如果用户选择 "no"，则将其设置为 false）。

示例：

boolean keepRunning = true;
while( keepRunning ) {
  //ask for input, calculate, print - the bulk of your code above

  System.out.println("Would you like to do another? y/n");

  String userInput = ...; //get from scanner, I'll leave this as an excercise for you
  keepRunning = "y".equalsIgnoreCase( userInput ); //you might want to be more lenient here, e.g. also accept "yes" etc.
}

当用户选择 "no" 时，交替使用 while(true) 和 break;。

示例：

while( true ) {  //keep running until we stop it from the inside
  //same as above

  ...

  //break the loop if the user didn't select "y"
  if( !"y".equalsIgnoreCase( userInput ) ) {
    break;
  }
}

Answer 2

您好，请检查以下代码

 public static void main(String args[]){
 Scanner input = new Scanner(System.in); 
    DecimalFormat formatter = new DecimalFormat("#0.00");

    String CType, c1 = "US", c2 = "EUR", c3 = "RM", c4 = "SAR"; 
    double CValue , US, EUR, RM, SGD, SAR;

    char choice='Y';//modified
    System.out.println("Welcome to Bonus Calculator");
    do{//modified
    System.out.println("Enter any of the following Currencies:"); 
    System.out.print("US\n" +
                     "EUR\n" +
                     "RM\n" +
                     "SGD\n" +
                     "SAR: ");
    CType = input.next();



   if(CType.equalsIgnoreCase("US")){
     System.out.print("Enter Value: ");
     CValue = input.nextInt();

       EUR = CValue * .88;
       RM = CValue * 3.92;
       SGD = CValue * 1.35;
       SAR = CValue * 3.75;

   System.out.print("US = " + formatter.format(CValue) + "EUR =" + formatter.format(EUR) + "RM =" + formatter.format(RM) + "SGD =" + formatter.format(SGD) + "SAR =" + formatter.format(SAR));
   }
   System.out.println("\nDo you which to Continue if Yes press 'Y' other wise press 'N'");//modified
   choice = input.next().toCharArray()[0];//modified
}while(choice!='N');//modified
}

Answer 3

你可以使用 while(true) as

public static void main(String[] args) {


        Scanner input = new Scanner(System.in);
        DecimalFormat formatter = new DecimalFormat("#0.00");

        String CType, c1 = "US", c2 = "EUR", c3 = "RM", c4 = "SAR";
        double CValue , US, EUR, RM, SGD, SAR;


        System.out.println("Welcome to Bonus Calculator");
        while (true) {

            System.out.println("Enter any of the following Currencies:");
            System.out.print("US\n" +
                    "EUR\n" +
                    "RM\n" +
                    "SGD\n" +
                    "SAR: ");
            CType = input.next();
            if(CType.equalsIgnoreCase("EXIT"))
                break;


            if (CType.equalsIgnoreCase("US")) {
                System.out.print("Enter Value: ");
                CValue = input.nextInt();

                EUR = CValue * .88;
                RM = CValue * 3.92;
                SGD = CValue * 1.35;
                SAR = CValue * 3.75;

                System.out.print("US = " + formatter.format(CValue) + "EUR =" + formatter.format(EUR) + "RM =" + formatter.format(RM) + "SGD =" + formatter.format(SGD) + "SAR =" + formatter.format(SAR));

            } else if (CType.equalsIgnoreCase("EU")) {
                System.out.print("Enter Value: ");
                CValue = input.nextInt();
                US = CValue * 1.14;
                RM = US * 3.92;
                SGD = US * 1.35;
                SAR = US * 3.75;

                System.out.print("EUR = " + formatter.format(CValue) + " US = " + formatter.format(US) + " RM = " + formatter.format(RM) + " SGD = " + formatter.format(SGD) + " SAR = " + formatter.format(SAR));

            } else if (CType.equalsIgnoreCase("RM")) {
                System.out.print("Enter Value: ");
                CValue = input.nextInt();
                US = CValue * .26;
                EUR = US * .88;
                SGD = US * 1.35;
                SAR = US * 3.75;

                System.out.print("RM = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SGD = " + formatter.format(SGD) + " SAR = " + formatter.format(SAR));

            } else if (CType.equalsIgnoreCase("SGD")) {
                System.out.print("Enter Value: ");
                CValue = input.nextInt();
                US = CValue * 0.74;
                EUR = US * .88;
                RM = US * 3.92;
                SAR = US * 3.75;

                System.out.print("SGD = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SAR = " + formatter.format(SAR) + " RM = " + formatter.format(RM));

            } else if (CType.equalsIgnoreCase("SAR")) {
                System.out.print("Enter Value: ");
                CValue = input.nextInt();
                US = CValue * 0.39;
                EUR = US * .88;
                RM = US * 3.92;
                SGD = US * 1.35;

                System.out.print("SAR = " + formatter.format(CValue) + " US = " + formatter.format(US) + " EUR = " + formatter.format(EUR) + " SGD = " + formatter.format(SGD) + " RM = " + formatter.format(RM));

            }
        }

    }

当用户键入 EXIT 时，它会从 loop.You 退出，作为用户的一个选项。

执行 do while 和 exit

Implementing do while and exit

java

converter