ConvertNumberToDollar.java

import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

public class ConvertNumberToDollar {
    public static String convertNumberToDollar(String input) {
        String output = "";
        for (int i = 0; i < input.length(); i++) {
            char ch = input.charAt(i);
            if (ch >= '0' && ch <= '9') {
                ch = '$';
            }

            output = output + ch;
        }

        return output;
    } 

    public static void main(String [] args) {
        Scanner sc = new Scanner(System.in);
        String result = "";

        while(true) {
            //get word from keyboard
            String input = sc.nextLine();

            //if input is "quit" break;
            if ("quit".equals(input)) {
                break;
            }

            //if word has numbers then change number to '$'
            String convertedString = convertNumberToDollar(input);

            //save converted word to string
            result = result + convertedString;
            System.out.println(result);
        }        
    }
}