ReverseWords.java

import java.lang.StringBuilder;

class ReverseWords {

  public static String reverse_words(String str) {
    StringBuilder reversed = new StringBuilder();
    int last = 0;

    for (int i=0;i<str.length(); i++) {
      if (str.charAt(i) == ' ') {
        reversed.insert(0, str.substring(last, i));
        reversed.insert(0, " ");
        last = i+1;
      }
    }

    reversed.insert(0, str.substring(last));

    return reversed.toString();
  }

  public static void main(String[] args) {
    String str = "My name is Chris";

    System.out.println(str);
    System.out.println(reverse_words(str));

    str = "My name is    Chris";

    System.out.println(str);
    System.out.println(reverse_words(str));
  }
}