Scanner Java

import java.util.Scanner;
public class HangMan {
    public static void main(String[] args) {
        System.out.println("Enter Secrect Word");
        Scanner userInput=new Scanner(System.in);
        String secretString = userInput.next();
        StringBuilder b=new StringBuilder(secretString.length());
        for(int i=0;i<secretString.length();i++)
            b.append("*");
        char[] secretStringCharArray=secretString.toCharArray();
        int charCount=secretString.length();
        while(charCount>=0){
            System.out.println("Secrect Word :"+b.toString());
            System.out.println("Guess a letter :");
            char guessChar = userInput.next().toCharArray()[0];
            for(int i=0;i<secretStringCharArray.length;i++){
                if(guessChar==secretStringCharArray[i])
                    b.setCharAt(i,guessChar);
            }
        }

    }

}