CODEWITHSUNDEEP
javaloopsarrays
Roy
Roy

Reputation: 13

Loop through char array and count chars

I'm trying to optimize my Java code so I try things. In my search for a short way I produced the code here below. This throws an Exception. Can you tell me why? Can't I loop through a string by a char Array?

public class Input {

    public static void main(String[] args) {

        String check = "Dit moet toch gewoon te doen zijn !!";
        check = check.toLowerCase();

        int[] counter = {0, 0, 0, 0, 0};
        char[] vowel = {'a', 'e', 'i', 'o', 'u'};

        int total = 0;
        for (int i = 0; i < check.length(); i++)
            if (check.charAt(i) == vowel[i])
                counter[i]++;

        for (int t : counter)
            total += t;

        System.out.println("Aantal klinkers: \t" + total);

    }
}

Upvotes: 1

Views: 7629

Answers (5)

Chameera
Chameera

Reputation: 71

for (int i = 0; i < check.length(); i++)
     if (check.charAt(i) == vowel[i])
         counter[i]++;

This loop goes from 0 to check.length(); but your array vowel[] has 5 element. So it generate array out of bound exception.

Upvotes: 2

PeterK
PeterK

Reputation: 1723

You could use a regex for this operation:

Pattern vowels = Pattern.compile("(?i)[aeiou]");
String check = "Dit moet toch gewoon te doen zijn !!";

Matcher matcher = vowels.matcher(check);

while(matcher.find()) {
    System.out.println("found vowel: " + matcher.group());
}

Explanation of regex:

(?i) make pattern case insensitive, [aeiou] characters to match.

Upvotes: 0

kyle england
kyle england

Reputation: 118

You must have two loops One for going through each char in string and a for loop going through each vowel array like so

 for (int i = 0; i < check.length(); i++)
     for (int p = 0; p < vowel.length; p++)
         if (check.charAt(i) == vowel[p])
             counter[p]++;

Enjoy.

Upvotes: 0

Unihedron
Unihedron

Reputation: 11041

One more for the clever regex department so you don't have to make your string lowercase and lose the cases for vowels:

if (check.matches("(?i)[^a-z][a-z].*"))
    System.out.println("Vowels found: " + check.replaceAll("[^a-z]+", ""));

Upvotes: 0

Justin
Justin

Reputation: 2031

Your code reads like this: For each character in "check" if character at index in "check" is character at index in "vowel"

That's probably not what you're looking for. The exception you're getting is because there are only 5 characters in "vowel" but alot in "check" (i'm not counting)

Now, I'm assuming what you're wanting to do is actually count the number of each vowel in "check"

You should actually use a nested for loop in this case. 

for (int i = 0; i < check.length(); i++) {
    for (int v = 0; v < vowel.length; v++) {
        if (check.charAt(i) == vowel[v]) {
            counter[v]++;
            break;
        }
    }
}

Upvotes: 3

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