Alphanumeric

Overview

Module

• package: org.eclipse.dirigible.sdk.utils
• source: utils/Alphanumeric.java

Random string generators suitable for tokens, short identifiers, and one-shot secrets that fit a "human readable" requirement — no symbols, with no extra filtering of ambiguity-prone glyphs (0/O, 1/l); reach for a dedicated library if you need that.

The implementation is backed by java.security.SecureRandom, so the outputs are cryptographically random; cost is comparable to one nextInt per character. Use random(int, String) when you need to constrain the alphabet (e.g. uppercase-only for case-insensitive shortcodes), and randomNumeric(int) when only digits are wanted.

Key Features:

• Cryptographically random: Backed by SecureRandom — safe for tokens, password-reset codes, and one-time secrets.
• Custom alphabet support: Pass any non-empty charset string to random(int, String) for domain-specific shortcodes.
• Default length 16: All no-argument overloads emit a 16-character string by default.

Example Usage:

import org.eclipse.dirigible.sdk.utils.Alphanumeric;

// Default 16-char alphanumeric token
String token = Alphanumeric.random();

// 8-char uppercase-only shortcode for case-insensitive lookups
String code = Alphanumeric.random(8, "ABCDEFGHIJKLMNOPQRSTUVWXYZ");

// 6-digit OTP
String otp = Alphanumeric.randomNumeric(6);

Methods

random()

Generates a 16-character random alphanumeric string using both letter cases and digits.

public static String random();

Returns

• Type: String
• Description: A 16-character cryptographically random alphanumeric string.

random(int length)

Generates a random alphanumeric string of the requested length.

public static String random(int length);

Parameter	Type	Description
length	int	Desired output length. Must be non-negative.

Returns

• Type: String
• Description: A cryptographically random alphanumeric string of the requested length.

random(int length, String charset)

Generates a random string of the requested length drawn from the supplied character set.

public static String random(int length, String charset);

Parameter	Type	Description
length	int	Desired output length. Must be non-negative.
charset	String	Non-empty string whose characters form the alphabet to draw from.

Returns

• Type: String
• Description: A cryptographically random string of the requested length, drawn uniformly from charset.

randomAlpha()

Generates a 16-character random alphabetic string (mixed-case letters only, no digits).

public static String randomAlpha();

Returns

• Type: String
• Description: A 16-character cryptographically random alphabetic string.

randomAlpha(int length)

Generates a random alphabetic string of the requested length (mixed-case letters only, no digits).

public static String randomAlpha(int length);

Parameter	Type	Description
length	int	Desired output length. Must be non-negative.

Returns

• Type: String
• Description: A cryptographically random alphabetic string of the requested length.

randomNumeric()

Generates a 16-character random numeric string (digits only).

public static String randomNumeric();

Returns

• Type: String
• Description: A 16-character cryptographically random numeric string.

randomNumeric(int length)

Generates a random numeric string of the requested length — useful for OTPs and short numeric codes.

public static String randomNumeric(int length);

Parameter	Type	Description
length	int	Desired output length. Must be non-negative.

Returns

• Type: String
• Description: A cryptographically random numeric string of the requested length.