Validate UUID
In this article, we will take a look at 2 different ways to validate a UUID string in java with examples.
What is UUID ?
UUID stands for Universal Unique IDentifier.
A UUID is a unique identifier that is used to identify a device or a piece of data. UUIDs are typically generated by a device or a service, and are then used to identify that device or service.
UUID has a fixed format having 5 blocks where each block has a fixed length of digits as below
| Name | Length(Hex digits) |
|---|---|
| time_low | 8 |
| time_mid | 4 |
| time_high_and_version | 4 |
| variant_and_sequence | 4 |
| node | 12 |
Remember that UUID comprises of alphanumeric characters.
Reasons to validate
There are a couple of reasons to validate a UUID string in Java.
1. To make sure that a UUID string that is being passed to your Java application is in the correct format.
2. To validate a UUID string to make sure that it is not being used to spoof a device or service.
Validate UUID string in Java
There are 2 ways to validate a UUID string in Java.
1. Using java.util.UUID
This class has a static method fromString() that takes a string argument returns an object of java.util.UUID.
If the string is not in the correct format, then this method will throw an IllegalArgumentException. Example,
UUID valid = UUID.fromString("30de749c-10b8-4be0-a077-5eb486197a29");
System.out.println(valid);
UUID invalid= UUID.fromString("AF");
System.out.println(invalid);
Output is
30de749c-10b8-4be0-a077-5eb486197a29
Exception in thread “main” java.lang.IllegalArgumentException: Invalid UUID string: AF
at java.base/java.util.UUID.fromString1(UUID.java:280)
at java.base/java.util.UUID.fromString(UUID.java:258)
at com.codippa.UUIDValidator.main(UUIDValidator.java:34)
2. Using regex
Another way to validate a UUID string is to use a regular expression.
A regular expression is a pattern that can be used to match a string. There are a few different regular expressions that can be used to match a UUID string.
One of those is
This regular expression will match a UUID string that is in the correct format.
String regex = "^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$";
Pattern pattern = Pattern.compile(regex);
System.out.println(
pattern.matcher("c0d69b05-c468-4d28-9779-c433e7364be6").matches());
System.out.println(
pattern.matcher("ABFCD").matches());
Output is
true
false
Conclusion
This article demonstrated 2 different ways to validate UUID string in java.
First is using UUID class in java itself.
Second is to validate the UUID string against a regular expression based on the format of standard UUID.
