Scanner is trying to read more numbers than expected and skips some other numbers-CodePudding

import java.util.Scanner;

public class Main
{
    public static void main(String[] args) {
    
    Scanner scanner = new Scanner (System.in);
    
    System.out.println("Enter numbers, input ends with 0: ");
    int max = 0;
    int count = 0;
    while (scanner.nextInt() != 0 )
    {
        if (scanner.nextInt() > max)
        {
            max = scanner.nextInt();
            count = 1;
        }
        else if (scanner.nextInt() == max)
        {
            count  ;
        }
    
        }
    if (max == 0 && count == 0)
    {
     System.out.println("No numbers are entered except zero.");

    }
    else
    {
        System.out.println("The largest number is "   max);
        System.out.println("The occurence count of the largest number is "   count);
    }

    }
        
}

The above code is what I have managed to create thus far in an attempt to create a program that will identify the largest number, and also take a count of how many times that number is listed. I would also like the number 0 to trigger the end of the input sequence.

For example, if I type:

2 3 9 4 5 9 3 3 0

I should receive a max of 9 and a count of 2.

The code seems to work sometimes, and other times does not return any output when a sequence ending in 0 is entered. I also get an incorrect count but correct max other times.

Please help me understand what is going haywire with my code.

CodePudding user response：

Every time you invoke scanner.nextInt(), it's (waiting for and) reading another int from input.

The times when it doesn't seem to complete is when you enter a sequence without a multiple of 3 entries, e.g. 1 0: the while condition reads the 1; the if condition reads the 0 (which doesn't cause the loop to break); and the max = waits for you to enter another number.

Don't keep invoking it: assign int next = scanner.nextInt(), and use that value:

while (true) {
  int next = scanner.nextInt();

  if (next == 0) break;

  if (next > max) { ... }
  else if (next == max) { ... }
}

CodePudding user response：

#Mind you that as far as your while loop is concerned, no command in the while loop will be executed whenever you enter zero[0] as an input because what you instructed the while loop to do is to run when the input is not zero so no need putting a condition to check whether an input is zero or not.

Then just as @Andy Turner said with small editon to his code do this to get things done:


   //use the value "true" rather than any other condition to keep the loop in iteration.
//The boolean value "true" means continue  reading and accepting input forever unless there is a condition that will break out of it inside the while loop
while (true) {
  int next = scanner.nextInt();

  if (next == 0){
//Do your prefered stuff here when the input evaluates to zero and then break out of the loop.
 break;
}

  if (next > max) { ... }
  else if (next == max) { ... }
}