Java：如何在第一次输入后使用哨兵关闭循环（使用多个输入时）

Question

我花了几个小时试图解决这个问题，如果这是一个简单的解决方案，我深表歉意。

我想让这个程序更加人性化。目前一切正常，但哨兵要求我为行驶里程和使用的汽油输入“0”。我希望哨兵在我仅输入“0”英里后结束程序。这可能吗？

import java.util.Scanner;

public class Mileage

{

public static void main(String[] args)
{   //initialization
    Scanner sc = new Scanner(System.in);
    int miles = -1, gallons = -1,
            totalMiles = 0, totalGallons = 0;
    double average, runningAverage;
    //while loop with sentinel controlled repetition
    while (miles != 0 && gallons != 0)
    {   //get miles 
        System.out.println("Enter the amount of miles driven. (0 to exit)");
        miles = sc.nextInt();
        //get gallons
        System.out.println("Enter the amount of gallons used. (0 to exit)");
        gallons = sc.nextInt();
        //calc average
        average = (double) miles / gallons;

        //calc running average
        totalMiles += miles;
        totalGallons += gallons;
        runningAverage = (double) totalMiles / totalGallons;

        //output average only if values were entered, by using if statement
        if (miles != 0 && gallons != 0)
        {
            System.out.printf("Miles per gallon for this trip is %.1f%n", average);

            System.out.printf("Running average miles per gallon is %.1f%n", runningAverage);
        }
    }

}

}

Answer 1

我希望哨兵在我仅输入“0”英里后结束程序。

如果我明白你的要求，只需更改

while (miles != 0 && gallons != 0)

到

while (miles != 0)

和

System.out.println("Enter the amount of gallons used. (0 to exit)");

到

System.out.println("Enter the amount of gallons used.");

您可能会发现在 0 英里处终止循环更方便。喜欢，

miles = sc.nextInt();
if (miles == 0) {
    break;
}

否则会再次提示gallons

Answer 2

当你这样做时：

miles = sc.nextInt();

您可以像这样检查退出程序：

if(miles==0){
    System.exit(0);
}

就在之前：

System.out.println("Enter the amount of gallons used. (0 to exit)");

Java：如何在第一次输入后使用哨兵关闭循环（使用多个输入时）

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