How to Match Phone Numbers in a List to a Regex Pattern in Java ?

Regular Expressions are also known as regex or regexp. It is one of the powerful features of Java that helps in sequences of characters that define a search pattern. Nowadays it is widely used in computer science, programming, and text processing for tasks such as string matching, data extraction, and validation. In Java, the "java.util.regex" package set of tools for pattern matching.

In this article, we will learn how to match phone numbers in a list to a certain pattern using regex.

Java Program to Match Phone Numbers in the List to Regex Pattern

Step 1: Import All the Necessary Packages

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

Step 2: Define the Regex Pattern using Tokens in Java

Phone number contains only numeric value and some special characters according to countries. For example, Let's take a U.S. phone number.

Step 3: Create a method Match Phone Numbers

 public static void matcher(List<String> phoneNumbers)

Program to Match Phone Numbers in a List

Approach 1: Using Regex

Now create a separate method in class to Match Phone Numbers which are store in List.

Match: 123-456-7890
Match: 987.654.3210
Not a Match: 555-1234
Match: 1234567890

Approach 2: Using Matches

The matches() method is a convenient method provided by the String class in Java for checking if a string matches a given regular expression. When we use this method, we don't need to explicitly create a Matcher object from the Pattern class; the method internally takes care of that.

Old Approach (Using Matcher):

Pattern pattern = Pattern.compile(phoneNumberPattern);
Matcher matcher = pattern.matcher(phoneNumber);
if (matcher.matches()) {
 // Do something when the string matches the pattern
} else {
 // Do something else when the string does not match the pattern
}

Using matches() directly on the string:

if (phoneNumber.matches(phoneNumberPattern)) {
 // Do something when the string matches the pattern
} else {
 // Do something else when the string does not match the pattern
}

In the second approach, the matches() method is called directly on the string (phoneNumber), and it internally creates a Matcher object, applies the pattern, and checks if the entire string matches the pattern. It simplifies the code and is often more concise.

Match: 123-456-7890
Match: 987.654.3210
Not a valid U.S. phone number: 555-1234
Match: 1234567890

Explanation of the Program:

• Checking stored Phone Numbers in a list to a specific pattern using Regular Expression help in flexible and scalable for validating or extracting specific formats of data we use regular expression pattern.
• Customize the regex pattern helps to match critical as per your requirement.
• This approach is used in every kind of form validation before store data into database.