Reverse String Word by Word in Java

Not using the split function the code would look like:

public static void reverseSentance(String str) {
    StringBuilder revStr = new StringBuilder("");
    int end = str.length(); // substring takes the end index -1
    int counter = str.length()-1;
    for (int i = str.length()-1; i >= 0; i--) {     
        if (str.charAt(i) == ' ' || i == 0) {
            if (i != 0) {
                revStr.append(str.substring(i+1, end));
                revStr.append(" ");
            }
            else {
                revStr.append(str.substring(i,end));
            }
            end = counter;
        }
        counter--;
    }
    System.out.println(revStr);
}