Module com.github.f4b6a3.ulid
Package com.github.f4b6a3.ulid

Class UlidCreator

  • public final class UlidCreator
extends Object
    A class that generates ULIDs.

    Both types of ULID can be easily created by this generator, i.e. monotonic and non-monotonic.

    In addition, a "non-standard" hash-based ULID can also be generated, in which the random component is replaced with the first 10 bytes of an SHA-256 hash.

    • Method Detail

      • getUlid

        public static Ulid getUlid()
        Returns a ULID.

        The random component is reset for each new ULID generated.

        Returns:
        a ULID

      • getUlid

        public static Ulid getUlid​(long time)
        Returns a ULID.

        The random component is reset for each new ULID generated.

        Parameters:
        time - the current time in milliseconds, measured from the UNIX epoch of 1970-01-01T00:00Z (UTC)
        Returns:
        a ULID

      • getMonotonicUlid

        public static Ulid getMonotonicUlid()
        Returns a Monotonic ULID.

        The random component is incremented for each new ULID generated in the same millisecond.

        Returns:
        a ULID

      • getMonotonicUlid

        public static Ulid getMonotonicUlid​(long time)
        Returns a Monotonic ULID.

        The random component is incremented for each new ULID generated in the same millisecond.

        Parameters:
        time - the current time in milliseconds, measured from the UNIX epoch of 1970-01-01T00:00Z (UTC)
        Returns:
        a ULID

      • getHashUlid

        public static Ulid getHashUlid​(long time,
                               String string)
        Returns a Hash ULID.

        The random component is replaced with the first 10 bytes of an SHA-256 hash.

        It always returns the same ULID for a specific pair of time and string.

        Usage example: 

        
 long time = file.getCreatedAt();
 String name = file.getFileName();
 Ulid ulid = UlidCreator.getHashUlid(time, name);
        Parameters:
        time - the time in milliseconds, measured from the UNIX epoch of 1970-01-01T00:00Z (UTC)
        string - a string to be hashed using SHA-256 algorithm.
        Returns:
        a ULID
        Since:
        5.2.0

      • getHashUlid

        public static Ulid getHashUlid​(long time,
                               byte[] bytes)
        Returns a Hash ULID.

        The random component is replaced with the first 10 bytes of an SHA-256 hash.

        It always returns the same ULID for a specific pair of time and bytes.

        Usage example: 

        
 long time = file.getCreatedAt();
 byte[] bytes = file.getFileBinary();
 Ulid ulid = UlidCreator.getHashUlid(time, bytes);
        Parameters:
        time - the time in milliseconds, measured from the UNIX epoch of 1970-01-01T00:00Z (UTC)
        bytes - a byte array to be hashed using SHA-256 algorithm.
        Returns:
        a ULID
        Since:
        5.2.0