While loop won't loop

Question

My while loop for some reason keeps skipping over my input line. My code is as follows:

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

Once it gets to the end of the loop where it asks you if you want to eat again,the while loop just terminates right there and goes to the end of the program instead of giving me the option to input. I can't figure out why it's doing that. Thanks in advance.

kviiri · Accepted Answer · 2013-11-21 17:02:24Z

3

This is because of how Scanner.nextInt() and Scanner.nextLine() work. If the Scanner reads an int and then ends up at the end of the line, Scanner.nextLine() will instantly just notice the line break and give you the remaining line (which is empty).

After the nextInt() call, add a input.nextLine() call:

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

That should fix it.

answered Nov 21, 2013 at 17:02

kviiri

3,3021 gold badge24 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Masudul · Accepted Answer · 2013-11-21 17:10:13Z

0

My while loop for some reason keeps skipping over my input line.

Use next() instead of nextLine(). Change your while loop like below:

  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();
     //....
  }

answered Nov 21, 2013 at 17:10

Masudul

22k5 gold badges45 silver badges60 bronze badges

Collectives™ on Stack Overflow

While loop won't loop

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related