Java Data Type - 如何获取大写字符串中每个单词的第一个字母

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    System.out.println("Enter a string");
    Scanner input = new Scanner(System.in);
    String s1 = input.nextLine();
    s1 = s1.trim();
    int howLong = s1.length();

    for (int counter = 0; counter < howLong; counter++) {
      char ch = s1.charAt(counter);
      System.out.print(ch);
    }

  }
}