Syntax error Java program to print first letter of each word using regex

Java program to print first letter of each word using regex

In this article, we will understand how to print the 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.

Problem Statement

Write a program in Java to print the first letter of each word using regex. Below is a demonstration of the same ?

Input 

Input String_1: Java Program
Input String_2: Joy of learning

Output

Result_1: JP
Result_2: Jol

Using main() method

Following are the steps to print the first letter of each word under the main() method ?

  • First, we will import the regex Matcher class and Pattern class using java.util.regex to use regular expressions.
  • Create two sample strings, input_string_1 and input_string_2, to apply the pattern to.
  • Define a regex pattern using Pattern.compile("\b[a-zA-Z]") to match the first letter of each word.
  • Use a Matcher object to apply the pattern on the strings. Loop through the matches and print the first letter of each word using the while loop.
  • Print the matched characters for each string, showing only the first letters of each word.

Example

Here, we bind all the operations together under the main() method ?

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

Using encapsulation

Following are the steps to print the first letter of each word using object-oriented programming ?

  • First, we will import the Matcher class and Pattern class using java.util.regex to use regular expressions.
  • Create print_regex_string(String s), which takes a string as input and performs the regex operations to print the first letter of each word.
  • In print_regex_string(), use Pattern.compile() to match the first letter of each word.
  • Within the method, use Matcher to find each match and print the result.
  • Call print_regex_string() on each string, encapsulating the logic for finding and printing initials.

Example

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
Updated on: 2024-10-29T00:38:40+05:30

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