Base64Url encoded uuids

base64UUID.java

import java.nio.ByteBuffer;
import java.util.UUID;
import java.util.Base64;


class Main {

  public static UUID uuid() {
    return UUID.randomUUID();
  }

  public static String uuidToBase64UrlString(UUID uuid) {
    ByteBuffer bb = ByteBuffer.allocate(16)
      .putLong(uuid.getMostSignificantBits());
      .putLong(uuid.getLeastSignificantBits());
    return Base64.getUrlEncoder().withoutPadding().encodeToString(bb.array());
  }

  public static UUID base64UrlStringToUUID(String uuid) {
    ByteBuffer bb = ByteBuffer.wrap(Base64.getUrlDecoder().decode(uuid));
    return new UUID(bb.getLong(), bb.getLong());
  }

  public static void main(String[] args) throws URISyntaxException {
    // create a v4 uuid
    UUID uuid = uuid();
    System.out.println(uuid.toString());
    
    String encodedUuid = uuidToBase64UrlString(uuid);
    System.out.println(encodedUuid);
    
    UUID decodedUuid = base64UrlStringToUUID(encodedUuid);
    System.out.println(decodedUuid.equals(uuid));
  }
}