SplitStringToParagraph.java

    /**
     * Split a single string into multiple paragraphs based on the last
     * punctuation found in the substring while iterating.
     *
     * @param dataString long string which is to be divided into paragraphs
     * @param maxAllowedLength number of maximum characters allowed in one
     * paragraph.
     * @return list of paragraphs
     */
    private static List<String> splitParagraph(String dataString, int maxAllowedLength) {
        int length = dataString.length();

        //find iterations count
        int iterations = length / maxAllowedLength;

        //to fetch remainging string of paragraph even if missed.
        iterations++;

        ArrayList<String> splitStringList = new ArrayList<>();

        //index for end of the previous paragraph
        int lastEnd = 0;
        for (int i = 0; i < iterations; i++) {

            //index of current End index of the paragraph
            int currentEnd = (lastEnd + maxAllowedLength
                    >= length) ? length : lastEnd + maxAllowedLength;

            //get sub string based on maxAllowedLength 
            String subString = dataString.substring(lastEnd, currentEnd);

            //find existing punctuation from the string
            char punctuation = getExisitingPunctuation(subString);
            //if not last ieration set last index of punctuation as currentEnd
            if (iterations + 1 != i) {
                int adjustedEndIndex = subString.lastIndexOf(punctuation);
                if (adjustedEndIndex != -1) {
                    currentEnd = lastEnd + adjustedEndIndex + 1;
                }
            }

            //get a new substring based on the updated indices
            subString = dataString.substring(lastEnd, currentEnd);

            //add the substring to the list
            splitStringList.add(subString);

            //update lastEnd index
            if (currentEnd < length) {
                lastEnd = currentEnd + 1;
            }
        }
        return splitStringList;
    }

    /**
     * Find a valid punctuation in the given string to split it into a natural
     * paragraph.
     *
     * @param subString source string in which we need to find the punctuation
     * @return valid punctuation character from the string
     */
    private static char getExisitingPunctuation(String subString) {
        char punctuation = '.';
        if (subString.contains(",")) {
            return ',';
        }
        if (subString.contains("!")) {
            return '!';
        }
        if (subString.contains("?")) {
            return '?';
        }
        return punctuation;
    }