How to find first character in words of a sentence?

import java.io.*;

class Initials

{

public static void main(String args[])throws IOException

{

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

String s;

char x;

int l;

System.out.print("Enter any sentence: ");

s=br.readLine();

s=" "+s; //adding a space infront of the inputted sentence or a name

s=s.toUpperCase(); //converting the sentence into Upper Case (Capital Letters)

l=s.length(); //finding the length of the sentence</span>

System.out.print("Output = ");


for(int i=0;i<l;i++)

{

x=s.charAt(i); //taking out one character at a time from the sentence

if(x==' ') //if the character is a space, printing the next Character along with a fullstop

System.out.print(s.charAt(i+1)+".");

}

}

}