Example: SumNumbersInStringByIteration in Java

// SumNumbersInStringByIteration
public class Main {
    public static void main(String[] args) {
        String inputString = "I have 10 apples, 5 bananas, and 2 dozens of grapes, costing $15 total.";
        int sum = 0;
        StringBuilder currentNumber = new StringBuilder();

        // Step 1: Iterate through each character of the string
        for (int i = 0; i < inputString.length(); i++) {
            char ch = inputString.charAt(i);

            // Step 2: Check if the character is a digit
            if (Character.isDigit(ch)) {
                currentNumber.append(ch); // Append digit to current number string
            } else {
                // Step 3: If not a digit, and we have a number built, parse and add it to sum
                if (currentNumber.length() > 0) {
                    sum += Integer.parseInt(currentNumber.toString());
                    currentNumber.setLength(0); // Reset StringBuilder for the next number
                }
            }
        }

        // Step 4: After the loop, check if there's a number at the very end of the string
        if (currentNumber.length() > 0) {
            sum += Integer.parseInt(currentNumber.toString());
        }

        System.out.println("The original string is: \"" + inputString + "\"");
        System.out.println("Sum of numbers: " + sum);
    }
}