java – replace number to word

String s = input.next();

for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
    switch (c) {
    case '0':
        System.out.println("zero"); 
        break;
    case '3':
        System.out.println("three");
        break;
    case '8':
        System.out.println("eight");
    default:
        System.out.println(c);

Input:
I have 3 Networking books, 0 Database books, and 8 Programming books.
Output: I have three Networking books, zero Database books, and eight Programming books.