How to Match Phone Numbers in a List to a Regex Pattern in Java ?
Last Updated :
12 Mar, 2024
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.
Java
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java. util.List;
class GFG {
public static void main (String[] args) {
String phoneNumberPattern = "\\b\\d{3}[-.]?\\d{3}[-.]?\\d{4}\\b";
}
}
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.
Java
// Java Program to Match Phone
// Numbers in a List Using Regex
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.List;
public class PhoneNumberMatcher {
// Created Macher function
public static void matcher(List<String> phoneNumbers)
{
// created phone number pattern using tokens
String phoneNumberPattern
= "\\b\\d{3}[-.]?\\d{3}[-.]?\\d{4}\\b";
// Compile the custom pattern using Pattern class
Pattern pattern
= Pattern.compile(phoneNumberPattern);
// Using for each loop check each element in list
for (String phoneNumber : phoneNumbers) {
//Using Matcher class matching phone number
Matcher matcher = pattern.matcher(phoneNumber);
if (matcher.matches()) {
System.out.println("Match: " + phoneNumber);
}
else {
System.out.println("Not a Match: "
+ phoneNumber);
}
}
}
public static void main(String[] args)
{
//List of U.S phone numbers
List<String> phoneNumbers
= List.of("123-456-7890", "987.654.3210",
"555-1234", "1234567890");
// Calling each method against the pattern
matcher(phoneNumbers);
}
}
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.
Java
// Java Program to Match Phone
// Numbers in a List Using matches() method
import java.util.List;
public class PhoneNumberMatcher {
// Created Macher function
public static void matcher(List<String> phoneNumbers) {
// created phone number pattern using tokens
String phoneNumberPattern = "\\b\\d{3}[-.]?\\d{3}[-.]?\\d{4}\\b";
// Using for each loop check each element in list
for (String phoneNumber : phoneNumbers) {
// Using matches() directly on the string
if (phoneNumber.matches(phoneNumberPattern)) {
System.out.println("Match: " + phoneNumber);
} else {
System.out.println("Not a valid U.S. phone number: " + phoneNumber);
}
}
}
public static void main(String[] args) {
// List of U.S phone numbers
List<String> phoneNumbers = List.of("123-456-7890", "987.654.3210", "555-1234", "1234567890");
// Calling each method against the pattern
matcher(phoneNumbers);
}
}
//This Code is Contributed by Ayan Ahmad
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.
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