Java Program to Print first letter of each word using regex

In this article, we will understand how to print first letter of each word using regex. A regular expression is a sequence of characters that forms a search pattern. A regular expression can be a single character, or a more complicated pattern.

A regular expression helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern. They can be used to search, edit, or manipulate text and data.

Below is a demonstration of the same −

Suppose our input is −

Input String_1: Java Program
Input String_2: Joy of learning

The desired output would be −

Result_1: JP
Result_2: Jol

Algorithm

Step 1 - START
Step 2 - Declare two string values namely input_string_1 and input_string_2. Declare a regex Pattern namely string_pattern and a Matcher object namely string_matcher.
Step 3 - Define the values.
Step 4 - Using a while-loop, compute string_matcher.group() to fetch the first letter of each word.
Step 5 - Display the result
Step 6 - Stop

Example 1

Here, we bind all the operations together under the ‘main’ function.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Regex {
   public static void main(String[] args) {
      System.out.println("Required packages have been imported");
      String input_string_1 = "Java Program";
      System.out.println("\nThe first string is defined as: " +input_string_1);
      Pattern string_pattern = Pattern.compile("\\b[a-zA-Z]");
      Matcher string_matcher = string_pattern.matcher(input_string_1);
      System.out.println("The first letters of the string is : ");
      while (string_matcher.find())
         System.out.print(string_matcher.group());
      System.out.println();
      String input_string_2 = "Joy of learning";
      System.out.println("\nThe second string is defined as: " +input_string_2);
      Matcher string_matcher_2 = string_pattern.matcher(input_string_2);
      System.out.println("The first letters of the string is : ");
      while (string_matcher_2.find())
         System.out.print(string_matcher_2.group());
      System.out.println();
   }
}

Output

Required packages have been imported

The first string is defined as: Java Program
The first letters of the string is :
JP

The second string is defined as: Java Program
The first letters of the string is :
Jol

Example 2

Here, we encapsulate the operations into functions exhibiting object-oriented programming.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Regex {
   static void print_regex_string(String s) {
      Pattern string_pattern = Pattern.compile("\\b[a-zA-Z]");
      Matcher string_matcher = string_pattern.matcher(s);
      System.out.println("The first letters of the string is : ");
      while (string_matcher.find())
         System.out.print(string_matcher.group());
      System.out.println();
   }
   public static void main(String[] args) {
      System.out.println("Required packages have been imported");
      String input_string_1 = "Java Program";
      System.out.println("\nThe first string is defined as: " +input_string_1);
      print_regex_string(input_string_1);
      String input_string_2 = "Joy of learning";
      System.out.println("\nThe second string is defined as: " +input_string_1);
      print_regex_string(input_string_2);
   }
}

Output

Required packages have been imported

The first string is defined as: Java Program
The first letters of the string is :
JP

The second string is defined as: Java Program
The first letters of the string is :
Jol