Capitalize specific character from HashMap String

I have a program which converts numbers 0-9 in a String to their text equivalents (e.g: "0" becomes "zero"). However, when the number is at the beginning of the sentence I need to capitalize it.

Example

4 dogs were chasing 3 cats.
The 8 eggs were separated into 3 groups. 

Becomes:

four dogs were chasing three cats.
The eight eggs were separated into three groups. 

Code

public String ConvertSentance(String s){
    sb = new StringBuilder();

    h.put("0","zero");
    h.put("1","one");
    h.put("2", "two");
    h.put("3", "three");
    h.put("4", "four");
    h.put("5", "five");
    h.put("6", "six");
    h.put("7", "seven");
    h.put("8", "eight");
    h.put("9", "nine");

    String[] split = s.split(" ");

    for (String newS : split) {
        if (h.containsKey(newS)) {
            sb.append(h.get(newS));
            sb.append(' ');
        }
        else {
            sb.append(newS);
            sb.append(' ');
        }
    }

    convertedSent = sb.toString();
    return sb.toString();

}

How could I get this to capitalize the beginning character so that the output turns into this?

Four dogs were chasing three cats.

I am having trouble getting this to work only when they number is at the beginning of the sentence. I have tried different variations of for-loops with no success.