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javauuid

How to create Unique Id in Java

I have a code like below:

D00077B4-EBFB-4BD8-9E3F-1F3943CBCE35

I was wondering how I could generate a code like this in Java.

Solution

  • This is a UUID, "a 128-bit number used to identify information in computer systems".

    The format is explained as:

    In its canonical textual representation, the sixteen octets of a UUID are represented as 32 hexadecimal (base 16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and four hyphens). For example:

    123e4567-e89b-12d3-a456-426655440000
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

    How to generate the code like this using Java?

    // Create a random UUID:
UUID uuid1 = UUID.randomUUID();
System.out.println(uuid1);

// Create a fixed UUID:
String uuidString = "D00077B4-EBFB-4BD8-9E3F-1F3943CBCE35";
UUID uuid2 = UUID.fromString(uuidString);
System.out.println(uuid2);

// Get string from UUID:
UUID uuid = ...
String s = uuid.toString();
System.out.println(s);