The metacharacter “\b” matches for the word boundaries and [a-zA-Z] matches one character from the English alphabet (both cases). In short, the expression \\b[a-zA-Z] matches one single character from the English alphabet, both cases after every word boundary.
Therefore, to retrieve the first letter of each word −
Compile the above expression of the compile() method of the Pattern class.
Get the Matcher object bypassing the required input string as a parameter to the matcher() method of the Pattern class.
Finally, for each match get the matched characters by invoking the group() method.
Example
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class FirstLetterExample {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter sample text: ");
String data = sc.nextLine();
String regex = "\\b[a-zA-Z]";
//Creating a pattern object
Pattern pattern = Pattern.compile(regex);
//Creating a Matcher object
Matcher matcher = pattern.matcher(data);
System.out.println("First letter of each word from the given string: ");
while(matcher.find()) {
System.out.print(matcher.group()+" ");
}
}
}Output
Enter sample text: National Intelligence Agency Research & Analysis Wing First letter of each word from the given string: N I A R A W