Home » Core Java » util » regex » Find occurances of a letter in a string

About Ilias Tsagklis

Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Find occurances of a letter in a string

In this example we shall show you how to find occurances of a specific letter in a String. To find occurances of a letter in a String one should perform the following steps:

  • Compile a given String regular expression to a Pattern, using compile(string regex) API method of Pattern. The given regex in the example is a word boundary followed by character “A”, then a character of any letter one or more times and then a word boundary again.
  • Use matcher(CharSequence input) API method of Pattern to create a Matcher that will match the given String input against this pattern.
  • While the matcher finds the next subsequence of the input sequence that matches the pattern, with find() API method of Matcher get the input subsequence matched, with group() API method of Matcher and print it,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {

    public static void main(String args[]) throws Exception {


  String candidate = "this is a test, A TEST.";


  String regex = "\bA\\w*\b";

  Pattern p = Pattern.compile(regex);


  Matcher m = p.matcher(candidate);

  String val = null;

  System.out.println("INPUT: " + candidate);


  System.out.println("REGEX: " + regex + "rn");


  while (m.find()) {


val = m.group();


System.out.println("MATCH: " + val);

  }


  if (val == null) {


System.out.println("NO MATCHES: ");

  }
    }
}

Output:

INPUT: this is a test, A TEST.
REGEX: bAw*b

MATCH: A

 
This was an example of how to find occurances of a letter in a String in Java.

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you our best selling eBooks for FREE!

 

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

 

and many more ....

 

Receive Java & Developer job alerts in your Area

I have read and agree to the terms & conditions

 

Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Inline Feedbacks
View all comments