为我的 java 类做一个更改程序，不知道如何循环整个程序？

Question

目前我正在开发一个程序，在该程序中用户输入一个以美分为单位的值（因此 1.25 美元将是 125），该程序会确定以最少的金额提供多少硬币。我有这个工作。

困扰我的是，我的教授希望程序不断循环，直到用户输入小于 0 的值。我不知道该怎么做，因为每次我尝试时，它只会循环一次，而不是显示适当数量的硬币。

请帮忙。

这是我的代码：

import java.util.Scanner;

public class MakingChange {

    public static void main(String[] args) { 
        //Prompts user to input the change they recieved.
        Scanner sc = new Scanner(System.in);
        System.out.println("Please enter the amount of change you recieved in coin format. Example: $1.25     would be entered as 125."); 
        int Change = sc.nextInt(); //The value is then stored as an integer named Change.

        int Pennies = 0;
        int Nickels = 0;
        int Dimes = 0;
        int Quarters = 0;

        while (Change < 1){
            System.out.println("Error: Cannot enter a value less than 1!");
            //System.exit(0); //found at http://codingforums.com/java-jsp/69296-%5Bjava%5D-how-end-program.html
        }

        while (Change > 0){ //Runs a loop which determines how many of each coin is used by subtracting the values of the largest first and continuing until 0.
            if (Change >= 25){
                Change -= 25;
                Quarters++;
            }
            else if (Change >= 10){
                Change -= 10;
                Dimes++;
            }
            else if (Change >= 5){
                Change -=5;
                Dimes++;
            }
            else if (Change >= 1){
                Change -= 1;
                Pennies++;
            }


        }
        System.out.println("In total, you should have recieved:");
        System.out.printf("Number of Quarters: %3d  %n", Quarters);
        System.out.printf("Number of Dimes: %6d  %n", Dimes);
        System.out.printf("Number of Nickels: %4d  %n", Nickels);
        System.out.printf("Number of Pennies: %4d  %n", Pennies);
        //Prints out final number of coins used by type of coin.
    }

}

Answer 1

废弃你的第一个 while 循环。您不希望两个循环处理同一件事。接下来，初始化您的“更改”变量，但将sc.nextInt(); 移动到内部，以便每次迭代都获取输入。最后，将循环设为 do-while 循环，使其至少运行一次（或者您可以将更改初始化为 1）。

int Change = 0;
do{
  Change = sc.nextInt();
  // ...
}
while(Change > 0);

Answer 2

您需要询问用户他们在循环中获得了多少变化。下面是一些代码：

import java.util.scanner;
public void MakingChange {
public static void main(String[] args) {
int change = 0;
int currentchange = 0;
Scanner in = new Scanner(System.in);
do {
change += currentchange;
System.out.println("Enter an amount of change.");
currentchange = in.nextInt();
} while(currentchange > 0);
}
}
System.out.println("Total change: " + change);

+1 To Gary for do 循环的想法。 你明白了。

Answer 3

我在您的代码中发现了一些问题，Java 命名约定的变量以小写字母开头。接下来，您可以简单地循环 Scanner.hasNextInt()。然后，如果您在自己的循环中计算硬币、硬币和镍币（您的镍币计数器计为硬币），您的代码似乎会更简单。所以，像 -

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String msg = "Please enter the amount of change "
            + "you received in coin format. Example: "
            + "$1.25 would be entered as 125.";
    System.out.println(msg);
    while (sc.hasNextInt()) {
        int change = sc.nextInt();
        int pennies = 0;
        int nickels = 0;
        int dimes = 0;
        int quarters = 0;

        if (change < 1) {
            System.out.println("Error: Cannot enter a value less than 1!");
        } else {
            while (change >= 25) {
                change -= 25;
                quarters++;
            }
            while (change >= 10) {
                change -= 10;
                dimes++;
            }
            while (change >= 5) {
                change -= 5;
                nickels++;
            }
            pennies = change;
        }
        System.out.println("In total, you should have recieved:");
        System.out.printf("Number of Quarters: %3d  %n", quarters);
        System.out.printf("Number of Dimes: %6d  %n", dimes);
        System.out.printf("Number of Nickels: %4d  %n", nickels);
        System.out.printf("Number of Pennies: %4d  %n", pennies);
        System.out.println(msg);
    }
}

Answer 4

我会像这样简化你的循环：

int change;
while ((change = sc.nextInt()) >= 0) {
    //do code
}

由于 Java 命名约定，请注意小写 change。

您的代码原样的主要问题是您有两个循环，如果您的数字不小于 1，您将立即退出第一个循环（如果小于 1，则无限循环）。你做了一次验证，然后做了你的程序逻辑。尝试使用单个循环。

Answer 5

您需要围绕所有内容进行循环。循环顶部会提示并读取值，循环底部会打印输出。但是因为是循环，所以会返回并再次提示。在给定的代码中，您没有该级别的循环。

Answer 6

import java.util.Scanner;

public class MakingChange {

public static void main(String[] args) { 
    //Prompts user to input the change they recieved.
    Scanner sc = new Scanner(System.in);

    int input = 0;
    do{
        System.out.println("Please enter the amount of change you recieved in coin format. Example: $1.25     would be entered as 125."); 
        input= sc.nextInt(); //The value is then stored as an integer named Change.
        if(input<=0) {
         System.out.println("Good Bye");
         break; breaks the loop
        }
    else{
        Change=input;
        int Pennies = 0;
        int Nickels = 0;
        int Dimes = 0;
        int Quarters = 0;

        while (Change > 0){ //Runs a loop which determines how many of each coin is used by subtracting the values of the largest first and continuing until 0.
            if (Change >= 25){
                 Change -= 25;
                Quarters++;
           }
          else if (Change >= 10){
            Change -= 10;
            Dimes++;
          }
          else if (Change >= 5){
            Change -=5;
            Dimes++;
          }
          else if (Change >= 1){
            Change -= 1;
            Pennies++;
          }
       }
       System.out.println("In total, you should have recieved:");
       System.out.printf("Number of Quarters: %3d  %n", Quarters);
       System.out.printf("Number of Dimes: %6d  %n", Dimes);
       System.out.printf("Number of Nickels: %4d  %n", Nickels);
       System.out.printf("Number of Pennies: %4d  %n", Pennies);
    //Prints out final number of coins used by type of coin.
   }//end of else
  }while(input>0);//end of do while

}

Answer 7

只需创建一个 while 循环并一直引用它直到输入