Group Assignment Solution - Extended

public class GroupProject

{

    public static String weLoveTheLetterS(String word)

    {

        word = word.replaceAll(" ", "S");

        return word;

    }

    public static String weReallyLoveTheLetterS(String word)
    {
        String phrase = word;
        phrase = phrase.replaceAll(" ", "S");

        // extend
        char[] letters = phrase.toCharArray();
        int flag = 0;
            for (int i = 0;i < phrase.length();i++)
            {
                if(letters[i] != 's' && letters != 'S')
                {
                    if (flag == 0)
                    {
                        letters[i]='s';
                        flag=1;
                    }

                    else if (flag == 1)
                    {
                        letters[i]='S';
                        flag = 0;
                    }
                }
            }
        String answer = String.copyValueOf(letters);
        return answer;
    }

    public static boolean sequenceChecker(String stringToBeChecked,
            String sequence)
    {
        boolean check = false;

        if (stringToBeChecked.contains(sequence))
        {
            return true;
        }
        return check;
    }

    public static String replaceThis(String theWord, String letter1,
            String letter2)
    {
        String res1 = "";
        String res2 = "";
        res1 = theWord.replaceAll(letter1, " ");
        res2 = res1.replaceAll(letter2, " ");
        return res2;
    }

    public static void main(String[] args)

    {

        // extended questions - Q1

        String reallyLoveS = "I'd love it if every sentence that contained the letter s where the spaces are supposed to be";
        System.out.println("Ext. Q1: " + weReallyLoveTheLetterS(reallyLoveS));

        // extended questions - Q2

        System.out.println("Ext. Q2: ");
        String seqCheck = "abbcccdddeeefffgggiiisssiii!!!$$$";
        System.out.println(sequenceChecker(seqCheck, "abb"));
        System.out.println(sequenceChecker(seqCheck, "cdd"));
        System.out.println(sequenceChecker(seqCheck, "i!!"));
        System.out.println(sequenceChecker(seqCheck, "$$$"));
        System.out.println(sequenceChecker(seqCheck, "dsa"));

        // extended questions - Q3
        System.out.print("Ext. Q3: ");
        String repThis = "This is the word that will be replaced shortly";
        String lett1 = "e";
        String lett2 = "a";

        System.out.println(replaceThis(repThis, lett1, lett2));

    }

}