import java.util.*;
public class VowelCounter
{
  public static void main(String[] args)
  {
    Scanner keyboard = new Scanner(System.in);
    System.out.println("Input a series of characters: ");
    String letters = keyboard.next();
    int count = 0;
    for (int i = 0; i < letters.length(); i++)
    {
        char characters = letters.charAt(i);
        if (isVowel(characters) == true)
        {
            count++;
        }
    }
    System.out.println("The number of vowels is: " + count);
  }
  public static boolean isVowel(char characters)
  {
    boolean result;
      if(characters=='a' || characters=='e' || characters=='i' || characters=='o' || characters=='u')
        result = true;
      else
        result = false;
    return result;
}
}
The code works but im suppose to input "Spring break only comes once a year." which if i do with the spaces my program will only find the vowels of Spring. how do i make it so it will skip the spaces and read the whole sentence.
                        
This is your problem:
String letters = keyboard.next();
It has nothing to do with the vowel-counting part - but everything to do with reading the value. The Scanner.next() method will only read to the end of the token - which means it stops on whitespace, by default.
Change that to
String letters = keyboard.nextLine();
and you should be fine.
You should verify this is the problem by printing out the string you're working with, e.g.
System.out.println("Counting vowels in: " + letters);
                                
                            
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