Java 实现do-while和exit

由于对Java相当陌生，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。请在这件事上帮助我。到目前为止，我的代码是：

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));

   }

}

---

将所有代码包装在一个循环中，并使用一个布尔变量，如

keepRunning

，该变量初始化为true。在循环结束时，您询问用户（从扫描仪获取输入），然后检查输入是否表示“是”或“否”（或其他术语为true和false），并相应地设置

keepRunning

（如果用户选择“否”，则将其设置为false）

例如：

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.
}

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;
  }
}

或者使用

while（true）

和

break当用户选择“否”时

例如：

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.
}

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;
  }
}

将所有代码包装在一个循环中，并使用一个布尔变量，如
keepRunning
，该变量初始化为true。在循环结束时，您询问用户（从扫描仪获取输入），然后检查输入是否表示“是”或“否”（或其他术语为true和false），并相应地设置
keepRunning
（如果用户选择“否”，则将其设置为false）

例如：

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.
}

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;
  }
}

或者使用
while（true）
和
break当用户选择“否”时

例如：

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.
}

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;
  }
}

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
}

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
}

您可以使用while（true）作为

当用户键入EXIT时，它将退出循环。您必须作为用户的选项退出。
您可以使用while（true）作为

当用户键入EXIT时，它将退出循环。您必须作为用户的选项退出。
那么问题出在哪里？您似乎已经对Java有了一些了解，循环有什么问题吗？我不知道在何处以及如何让它要求用户输入另一个值，如果没有，则退出。我从代码中知道，我应该知道这一点。但是我迷路了。那么问题出在哪里呢？您似乎已经对Java有了一些了解，循环有什么问题吗？我不知道在何处以及如何让它要求用户输入另一个值，如果没有，则退出。我从代码中知道，我应该知道这一点。但是我迷路了。非常感谢你。我能够按要求完成并运行程序。祝你有愉快的一天@试试看。编码员我很高兴它奏效了，希望你也学到了一些东西：）-顺便说一句，别忘了接受答案。非常感谢。我能够按要求完成并运行程序。祝你有愉快的一天@试试看。编码员我很高兴它奏效了，希望你也学到了一些东西：）-顺便说一句，别忘了接受答案。