ProgMasters_StringCalculator

package stringcalculator;

public class StringCalculator {

    public static int add(String numbers) {

        if (numbers.isEmpty()) {
            return 0;
        } else if (numbers.length() > 1) {
            int i = 0;
            int j = 0;
            String temp = "";
            int sum = 0;

            for (i = 0; i < numbers.length(); i++) {
                if (Character.isDigit(numbers.charAt(i))) {
                    for (j = i; j < numbers.length(); j++) {
                        if (Character.isDigit(numbers.charAt(j))) {
                            temp += numbers.substring(j, j + 1);

                        } else {
                            break;
                        }
                        i = j;
                    }
                    int biggerThan = Integer.parseInt(temp);
                    if (biggerThan > 1000) {
                        biggerThan = 0;
                    } else
                        sum += biggerThan;
                    temp = "";
                }
            }
            return sum;
        }
        return Integer.parseInt(numbers);
    }
}