Stuck on how to "append a period" into an acronym

An acronym is a word formed from the initial letters of words in a set phrase. Define a method named createAcronym that takes a string parameter and returns the acronym of the string parameter. Append a period (.) after each letter in the acronym. If a word begins with a lower case letter, don't include that letter in the acronym. Then write a main program that reads a phrase from input, calls createAcronym() with the input phrase as argument, and outputs the returned acronym. Assume the input has at least one upper case letter.

Ex: If the input is:

Institute of Electrical and Electronics Engineers

the output should be:

I.E.E.E.

Ex: If the input is:

Association for computing MACHINERY

the output should be:

A.M.

The letters ACHINERY in MACHINERY don't start a word, so those letters are omitted.

The program must define and call a method:

public static String createAcronym(String userPhrase)

So far my code looks like this:

import java.util.Scanner;

public class LabProgram {
   
     public static String createAcronym(String userPhrase) {

       String[] separatedWords = userPhrase.split(" ");

       String acronymAlphabets = " ";

       for(int i = 0; i < separatedWords.length; ++i) {

           if(Character.isUpperCase(separatedWords [i].charAt(0))) {

               acronymAlphabets += Character.toUpperCase(separatedWords [i].charAt(0));

           }

       }

       return acronymAlphabets;

   }
   
   public static void main(String[] args) {
       Scanner userInput = new Scanner(System.in);

       System.out.println(createAcronym(userInput.nextLine()));
   }
}

The system returns the correct acronym but cant for the life of me figure out how to get the periods in the proper place. Side note: Im really good at getting them at the beginning or end of them. Any help "appending" this problem would be awesome!

Solution

Change
acronymAlphabets += Character.toUpperCase(separatedWords [i].charAt(0));
to
acronymAlphabets += Character.toUpperCase(separatedWords [i].charAt(0))+".";

Here is one way using streams.

String[] titles = {"Institute of Electrical and Electronics Engineers",     
    "Association for Computing MACHINERY",
    "Association of  Lions, and Tigers, and Bears, oh my!!"};

for (String title : titles) {
    System.out.println(createAcronym(title));
}

prints

I.E.E.E
A.C.M
A.L.T.B

Split on anything that isn't a word and stream the array
filter any words not starting with an upper case character.
Map the first letter of each word to a String.
and join together with a period between each word.

public static String createAcronym(String title) {
    return Arrays.stream(title.split("\\W+"))
            .filter(str -> Character.isUpperCase(str.charAt(0)))
            .map(str -> str.substring(0, 1))
            .collect(Collectors.joining("."));
}