Help with a program

[stormswimmer]

Hello everyone i am having trouble with this program that i am writing. The purpose of this program is to convert a string entered by a user into pig latin.
The rules of Pig Latin are,
No vowels in the English word, then the Pig Latin word is just the English word + "ay"

If the English word begins with a vowel, then the Pig Latin word is just the English word + "yay".

Otherwise (if the English word has a vowel in it and yet doesn't start with a vowel), then the Pig Latin word is end + start + "ay

When i run this program and i test phrases like "I green" i get "Iyay greenay".
here is my program

/**
 * This program translate a string into Pig Latin
 */
import java.util.*; 
import java.io.*; 
public class Piglatinator
{
    public static void main(String []args) throws IOException 
    {
        System.out.println("This program translate a string into Pig Latin"); 
        System.out.println("To end this program at any time just enter \"q\""); 
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); 
        String str = ""; 
        do
        {
            System.out.println("\nPlease enter a string"); 
            str = in.readLine();
            System.out.print(translateToPiglatin(str)); 
        }
        while (!str.equalsIgnoreCase("q") && !str.equalsIgnoreCase("quit")); 

    }
    public static String translateToPiglatin(String str) throws IOException 
    {
        StringTokenizer st = new StringTokenizer(str);
        int num = st.countTokens(); 
        String [] word = new String [num]; 
        int counter = 0; 
        String s = ""; 
        while (st.hasMoreTokens()) 
        {
            word [counter] = st.nextToken();
            if(calculateVowelPositions(word [counter]) == 0)
            {
                word[counter] = word[counter].concat("yay"); 
            }
            else if(word[counter].charAt(0) == 'a' || word[counter].charAt(0) == 'A' || word[counter].charAt(0) == 'e' || word[counter].charAt(0) == 'E' || word[counter].charAt(0) == 'i' || word[counter].charAt(0) == 'I' || word[counter].charAt(0) == 'o' || word[counter].charAt(0) == 'O' || word[counter].charAt(0) == 'u' || word[counter].charAt(0) == 'U')
            {
                word[counter] = str.toLowerCase(); 
                word[counter] = str.concat("ay"); 
            }
            else
            {      
                int vowel = calculateVowelPositions(str); 
                String end = word[counter].substring(0, vowel); 
                String front = word[counter].substring(vowel , word[counter].length());
                front = front + end + "ay";
                word [counter] = front;
            }
            s = s.concat(word [counter] + " "); 
            counter ++; 
        }
        return s;       
    }
    public static int calculateVowelPositions(String str) 
    {
        str = str.toLowerCase(); 
        str = str.trim(); 
        int position = 0; 
        for(int j = 0; j < str.length(); j ++)
        {
            if(str.charAt(j) == 'a')
            {
                position = j;
                break; 
            }
            else if (str.charAt(j) == 'e')
            {
                position = j;
                break;    
            }
            else if (str.charAt(j) == 'i')
            {
                position = j;
                break; 
            }
            else if(str.charAt(j) == 'o')
            {
                position = j;
                break; 
            }
            else if(str.charAt(j) == 'u')
            {
                position = j;
                break; 
            }
        }
        return position; 
    }
}

[destin]

Change:

int vowel = calculateVowelPositions(str);

to:

int vowel = calculateVowelPositions(word[counter]);

You had it only checking the first vowel of the whole String instead of a specific word.

[destin]

Btw, there are a few things you left out. For example, type in "quack". You'll get "uackqay". Another thing (you might run into some trouble with this), it's not just vowels, it's vowel sounds. hour become houryay, honest becomes honestyay, etc.