Java program to expand a String if range is given?

// Java Program to Illustrate Expansion of String

// Main class
public class StringExpand {

    // Method 1
    // To split the string
    static String[] split(String st)
    {
        // Count how many words in our string
        // Irrespective of spaces
        int wc = countWords(st);
        String w[] = new String[wc];
        char[] c = st.toCharArray();
        int k = 0;

        for (int i = 0; i < c.length; i++) {

            // Initially declaring and initializing
            // string as empty
            String s = "";

            // Whenever we found an non-space character
            while (i < c.length && c[i] != ' ') {

                // Concat with the String s
                // Increment the value of i
                s = s + c[i];
                i++;
            }

            // If the String is not empty
            if (s.length() != 0) {

                // Add the String to the String[]
                // array
                w[k] = s;
                k++;
            }
        }

        // Returning the string array
        return w;
    }

    // Method 2
    // To count the number of words in a string
    static int countWords(String str)
    {
        int count = 0;
        for (int i = 0; i < str.length(); i++) {

            // The below condition to check
            // whether the first character is
            // space or not
            if (i == 0 && str.charAt(i) != ' '
                || str.charAt(i) != ' '
                       && str.charAt(i - 1) == ' ') {
                count++;
            }
        }

        // Returning the count
        return count;
    }

    // Method 3
    // To expand the string
    public static void expand(String s)
    {
        String p = s;
        String[] arr = p.split("\\-");
        String k = "";

        // Traversing over array using for loop
        for (int i = 0; i < arr.length; i++) {

            // Case 1
            if (i != arr.length - 1) {

                String[] arr1 = arr[i].split(", ");
                String[] arr2 = arr[i + 1].split(", ");

                int a = Integer.parseInt(
                    arr1[arr1.length - 1]);
                int b = Integer.parseInt(arr2[0]);

                for (int j = a + 1; j < b; j++) {
                    arr[i] = arr[i] + ", " + j;
                }
            }

            // Case 2
            if (k != "")
                k = k + ", " + arr[i];

            // Case 3
            else
                k = k + arr[i];
        }

        // Print the expanded string
        System.out.println(k);
    }

    // Method 4
    // Main driver method
    public static void main(String[] args)
    {
        // Custom string input
        String s = "1-5, 8, 11-14, 18, 20, 26-29";

        // Calling the method 3 to
        // expand the string
        expand(s);
    }
}

// Java program to Expand a String if Range is Given

// Main class
// GenerateStringOnRange
class GFG {

    // Method 1
    // To generate string on range
    public static String generateStringOn(String input)
    {
        String[] words = input.split(" ");

        // Initially setting up range
        String[] ranges = null;
        int number = 0;

        // Creating a StringBuffer object so that
        // we can modify the string
        StringBuffer buffer = new StringBuffer();

        // Looking out for words by
        // iterating using for each loop
        for (String word : words) {
            
            // To be replaced by
            // using replace() method
            word = word.replace(",", "");

            // If word is containing "-" character
            if (word.contains("-")) {
                ranges = word.split("-");
                number = Integer.parseInt(ranges[0]);

                // Till number is within range
                while (number
                       <= Integer.parseInt(ranges[1])) {
                    
                    // Append , in between them
                    buffer.append(number + ", ");
                    number++;
                }
            }

            // If we reaches here then
            // word does contains "-"
            else {
                buffer.append(word + ", ");
            }
        }

        // Return the StringBuffer object
        return buffer.toString();
    }

    // Method 2
    // Main driver method
    public static void main(String[] args)
    {
        // Custom input string
        String input = "1-5, 8, 11-14, 18, 20, 26-29";

        // Calling the method 1 as created above 
        System.out.println(generateStringOn(input));
    }
}