RandomStringGenerator

A zero-dependency, fluent Java utility designed for generating customizable random strings, unique identifiers, and mock data using SecureRandom by default.

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Features

• Fluent Builder Pattern: Clean and expressive object construction.
• Cryptographically Secure: Defaults to SecureRandom with support for custom PRNG instances.
• Built-in Character Pools: Pre-configured sets including URL-Safe, Base58, Hexadecimal, and Alphanumeric.
• Batch & Stream Output: Generate single strings, unique immutable sets, immutable lists, or Java Streams.
• Prefixes & Suffixes: Direct formatting integration for custom token formats.

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Quick Start

1. Basic Generation

RandomStringGenerator generator = new RandomStringGenerator.Builder()
        .length(8)
        .build();

String token = generator.generate(); // e.g., "aB9xK2Lm"

2. Custom Pools & Formatting

RandomStringGenerator orderIdGen = new RandomStringGenerator.Builder()
        .pool(CharacterPool.HEXADECIMAL)
        .length(6)
        .prefix("ORD-")
        .suffix("-2026")
        .build();

String orderId = orderIdGen.generate(); // e.g., "ORD-4F9A12-2026"

3. Custom Character Sets

RandomStringGenerator pinGen = new RandomStringGenerator.Builder()
        .customPool("0123456789")
        .length(4)
        .build();

String pin = pinGen.generate(); // e.g., "4921"

4. Bulk Generation & Streams

RandomStringGenerator generator = new RandomStringGenerator.Builder()
        .pool(CharacterPool.BASE58)
        .length(4)
        .build();

// Generate an unmodifiable set of unique tokens
Set<String> uniqueTokens = generator.generateImmutableSet(3); // e.g., ["7kM9", "B3xT", "8wLc"]

// Stream generation: assembling a formatted multi-segment license key
String licenseKey = generator.generateStream(4)
        .collect(Collectors.joining("-")); // e.g., "7kM9-B3xT-8wLc-2vPq"

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Supported Character Pools

CharacterPool Enum	Character Set	Use Case
UPPERCASE	A-Z	Voucher codes, Serial numbers
LOWERCASE	a-z	Readable slugs
MIXEDCASE	A-Z, a-z	Case-sensitive identifiers
HEXADECIMAL	0-9, A-F	Hashes, Color codes, Byte IDs
ALPHANUMERIC_UPPERCASE	A-Z, 0-9	License keys, Gift codes
ALPHANUMERIC_LOWERCASE	a-z, 0-9	Database keys, URL slugs
ALPHANUMERIC_MIXEDCASE	A-Z, a-z, 0-9	Session tokens, General IDs
URL_SAFE	A-Z, a-z, 0-9, -_	Web tokens, Filenames
BASE58	Bitcoin Base58 Alphabet	High readability (no 0, O, I, l)

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License

This project is licensed under the MIT License - see the LICENSE file for details.