Java program that does simple string manipulation is not working correctly

Question

I wrote this program for school and it almost works, but there is one problem. The goal of the program is to take an inputted string and create a new string out of each word in the input beginning with a vowel.

Example:

input: It is a hot and humid day.
output: Itisaand.

Here is the driver:

public class Driver {

public static void main(String[] args) {

    Scanner console = new Scanner(System.in);
    System.out.print("Input: ");
    String input = console.nextLine();
    Class strings = new Class(input);
    int beg=0;
    for(int j=0;j<input.length();j++)
    {
        if(strings.isVowel(j)&&(j==0||input.charAt(j-1)==' '))
            beg=j;
        else if(strings.endWord(j)&&(beg==0||input.charAt(beg-1)==' '))
        {
            strings.findWord(beg, j);       
        }
    }
    System.out.print("Output: ");
    strings.printAnswer();
}

}

And here is the class:

public class Class {

    String input="",answer="";
    public Class(String input1)
    {
        input = input1;
    }


    public boolean isVowel(int loc)
    {
        return (input.charAt(loc)=='U'||input.charAt(loc)=='O'||input.charAt(loc)=='I'||input.charAt(loc)=='E'||input.charAt(loc)=='A'||input.charAt(loc)=='a'||input.charAt(loc)=='e'||input.charAt(loc)=='i'||input.charAt(loc)=='o'||input.charAt(loc)=='u');
    }
    public boolean endWord(int loc)
    {
        return (input.charAt(loc)==' '||input.charAt(loc)=='.'||input.charAt(loc)=='?'||input.charAt(loc)=='!');
    }
    public void findWord(int beg,int end)
    {
        answer = answer+(input.substring(beg,end));
    }
    public void printAnswer()
    {
        System.out.println(answer+".");
    }
}

With this code, i get the output:
Itisaa hotandand humidand humid summerand humid summer day.

By removing this piece of code:

&& (j == 0 || input.charAt(j-1) == ' ')

I get the proper output, but it doesn't work if an inputted word has more than one vowel in it.

For example:

input: Apples and bananas.
output: and.

Can someone please explain:
a) why the code is printing out words beginning with consonants as it is and
b) how I could fix it.

Also, the methods in the class I've written can't be changed.

Answer 1

Here's a better algorithm:

1. split the input into an array of words
2. iterate over each word
3. if the word begins with a vowel, append it to the output

The easiest way to split the input would be to use String.split().

Here's a simple implementation:

public static void main(String[] args) {
    Scanner console = new Scanner(System.in);
    String input = console.nextLine();
    String[] words = input.split(" ");
    StringBuilder output = new StringBuilder();
    for (String s : words) {
        if (startsWithVowel(s)) {
            output.append(s);
        }
        else {
            output.append(getPunc(s));
        }
    }
    System.out.println(output.toString());
}

public static boolean startsWithVowel(String s) {
     char[] vowels = { 'a', 'e', 'i', 'o', 'u' };
     char firstChar = s.toLowerCase().charAt(0);
     for (char v : vowels) {
         if (v == firstChar) {
             return true;
         }
     }
     return false;
 }

public static String getPunc(String s) {
    if (s.matches(".*[.,:;!?]$")) {
        int len = s.length();
        return s.substring(len - 1, len);
    }
    return "";
}

Answer 2

The problem with your code was: It was counting the same word multiple times, due to it finding vowels and starting the word search process over again.

Heres how I went about solving the problem, while still keeping your code looking relatively the same: All I changed was your loop

for(int i=0;i<input.length();i++)
    {
        if(strings.isVowel(i) &&(i==0 || strings.endWord(i-1))){ 
            beg = i;
            for(int j = i; j < input.length();j++) //look for end of word
            {
                if(strings.endWord(j)) //word has ended
                {
                    i = j; //start from end of last word
                    strings.findWord(beg, j);         
                    break; //word done, end word search
                }
            }
        }
    }

As mentioned above, there are better ways to go about this, and there are some pretty glaring flaws in the setup, but you wanted an answer, so here you go