UUID Apex

Uuid.cls

public class Uuid {
    static final String GROUP_SEP = '-';
    
    Uuid() {}
    
    public static String randomUuid() {
        String hex = EncodingUtil.convertToHex(Crypto.generateAesKey(128));
        
        return String.join(new String[] {
            hex.substring(0,8),
            hex.substring(8,12),
            hex.substring(12,16),
            hex.substring(16,20),
            hex.substring(20)
        }, GROUP_SEP);
    }
}

UuidX.cls

public class UuidX {
    static final Pattern SPLIT_PATTERN = Pattern.compile('\\p{XDigit}{8}(\\p{XDigit}{4}){3}\\p{XDigit}{12}');
    static final String GROUP_SEP = '-';
    static final String GROUP_FORMAT_STR = '{0}-{1}-{2}-{3}-{4}';

    UuidX() {}   
    
    public static String randomUuid_1() {
        // 10,000 iterations (Start: 19:26:13.08, End: 19:26:14.50, Duration: 00:01.42)
        return formatGroups(random128HexGrouped());
    }
    
    public static String randomUuid_2() {
        // 10,000 iterations (Start: 19:26:30.04, End: 19:26:30.05, Duration: 00:00.01)
        return joinGroups(random128HexGrouped());
    }
    
    public static String randomUuid_3() {
        // 10,000 iterations (Start: 19:34:18.07, End: 19:34:19.11, Duration: 00:01.04)
        return formatGroups(random128HexPatternSplitGrouped());
    }
    
    public static String randomUuid_4() {
        // 10,000 iterations (Start: 19:35:08.03, End: 19:35:09.18, Duration: 00:01.14)
        return joinGroups(random128HexPatternSplitGrouped());
    }
    
    static String formatGroups(String[] groups) {
        return String.format(GROUP_FORMAT_STR, random128HexGrouped());
    }
    
    static String joinGroups(String[] groups) {
        return String.join(random128HexGrouped(), GROUP_SEP);
    }
    
    static String[] random128HexPatternSplitGrouped() {
        return SPLIT_PATTERN.split(random128Hex());
    }
    
    static String[] random128HexGrouped() {
        String h = random128Hex();
        
        return new String[] {
            h.substring(0,8),
            h.substring(8,12),
            h.substring(12,16),
            h.substring(16,20),
            h.substring(20)
        };
    }
    
    static String random128Hex() {
        return EncodingUtil.convertToHex(Crypto.generateAesKey(128));
    }
}