In this regex tutorial, we will learn to validate user entered phone numbers for a specific format (in this example numbers are formatted in north American format) and if numbers are correct then reformat them to a standard format for display. I have tested formats including 1234567890, 123-456-7890, 123.456.7890, 123 456 7890, (123) 456 7890, and all such combinations.
Using Regex to Validate North American Phone Numbers
Regex : ^\\(?([0-9]{3})\\)?[-.\\s]?([0-9]{3})[-.\\s]?([0-9]{4})$
Above regular expression can be used to validate all formats of phone numbers to check if they are valid north American phone numbers.
List phoneNumbers = new ArrayList();
phoneNumbers.add("1234567890");
phoneNumbers.add("123-456-7890");
phoneNumbers.add("123.456.7890");
phoneNumbers.add("123 456 7890");
phoneNumbers.add("(123) 456 7890");
//Invalid phone numbers
phoneNumbers.add("12345678");
phoneNumbers.add("12-12-111");
String regex = "^\\(?([0-9]{3})\\)?[-.\\s]?([0-9]{3})[-.\\s]?([0-9]{4})$";
Pattern pattern = Pattern.compile(regex);
for(String email : phoneNumbers)
{
Matcher matcher = pattern.matcher(email);
System.out.println(email +" : "+ matcher.matches());
}
Output:
1234567890 : true
123-456-7890 : true
123.456.7890 : true
123 456 7890 : true
(123) 456 7890 : true
12345678 : false
12-12-111 : false
Using Regex to format North American Phone Numbers
Regex : ($1) $2-$3
Use above regex to reformat phone numbers validated in above step to reformat in a consistent way to store/display purpose.
List phoneNumbers = new ArrayList();
phoneNumbers.add("1234567890");
phoneNumbers.add("123-456-7890");
phoneNumbers.add("123.456.7890");
phoneNumbers.add("123 456 7890");
phoneNumbers.add("(123) 456 7890");
//Invalid phone numbers
phoneNumbers.add("12345678");
phoneNumbers.add("12-12-111");
String regex = "^\\(?([0-9]{3})\\)?[-.\\s]?([0-9]{3})[-.\\s]?([0-9]{4})$";
Pattern pattern = Pattern.compile(regex);
for(String email : phoneNumbers)
{
Matcher matcher = pattern.matcher(email);
//System.out.println(email +" : "+ matcher.matches());
//If phone number is correct then format it to (123)-456-7890
if(matcher.matches())
{
System.out.println(matcher.replaceFirst("($1) $2-$3"));
}
}
Output:
(123) 456-7890
(123) 456-7890
(123) 456-7890
(123) 456-7890
(123) 456-7890
Above regex will work in java-script as well. So keep these regex handy when you need them next time.
Happy Learning !!
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