Question

我的while循环由于某种原因不断跳过我的输入行。我的代码如下：

import java.util.Scanner;
public class CalorieCalculator {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    Calories[] array = {new Calories("spinach", 23), new Calories("potato", 160), new Calories("yogurt", 230), new Calories("milk", 85),
            new Calories("bread", 65), new Calories("rice", 178), new Calories("watermelon", 110), new Calories("papaya", 156),
            new Calories("tuna", 575), new Calories("lobster", 405)};
    System.out.print("Do you want to eat food <Y or N>? ");
    String answer = input.nextLine();
    int totalCal = 0;
    while (answer.equalsIgnoreCase("y")){
        System.out.print("What kind of food would you like?");
        String answer2 = input.nextLine();
        System.out.print("How many servings?: ");
        int servings = input.nextInt();
        for (int i = 0; i < array.length; i++){
            if (array[i].getName().equalsIgnoreCase(answer2))
                totalCal = totalCal + (servings*array[i].getCalorie());
        }//end for loop
        System.out.print("Do you want to eat more food <Y or N>? ");
        answer = input.nextLine();
    }//end while loop
    System.out.println("The total calories of your meal are " + totalCal);

}//end main method
}//end CalorieCalculator class

一旦它到达循环的末尾，它会询问你是否想再次进食，while循环就在那里终止并进入程序的结尾，而不是给我输入的选项。我无法弄清楚为什么会这样做。提前谢谢。

Answer 1

这是因为Scanner.nextInt()和Scanner.nextLine()的工作方式。如果Scanner读取int，然后在该行的末尾结束，Scanner.nextLine()会立即注意到换行符，并为您提供剩余行（为空）。< / p>

在nextInt()来电之后，添加input.nextLine()来电：

int servings = input.nextInt();
input.nextLine(); //this is the empty remainder of the line

那应该解决它。

Answer 2

我的while循环由于某种原因不断跳过我的输入行。

使用next()代替nextLine()。如下所示更改while循环：

  int totalCal = 0;
  while (true){
      System.out.print("Do you want to eat food <Y or N>? ");
     String answer = input.nextLine();

     if("N".equalsIgnoreCase(answer)){
         break;
     }

    System.out.print("What kind of food would you like?");
    String answer2 = input.next();
    System.out.print("How many servings?: ");
    int servings = input.nextInt();
     //....
  }

虽然循环不会循环

2 个答案: