commons

commons is a collection of lightweight, dependency-free Java utility libraries designed for everyday backend development.

Each module is independently published — pull only what you need.

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Modules

Module	Description	Version
commons-security	HMAC-SHA256 request signing and verification
commons-exception	Standardized API exceptions & factory
commons-model	API response wrappers & validation models
commons-utils	Utility classes and helper functions shared across commons modules.

More modules coming soon.

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Installation

Pick only the modules you need.

Maven

<dependency>
    <groupId>io.github.uncaughterrol</groupId>
    <artifactId>commons-security</artifactId>
    <version>0.6.0</version>
</dependency>

<dependency>
    <groupId>io.github.uncaughterrol</groupId>
    <artifactId>commons-exception</artifactId>
    <version>0.6.0</version>
</dependency>

<dependency>
    <groupId>io.github.uncaughterrol</groupId>
    <artifactId>commons-model</artifactId>
    <version>0.6.0</version>
</dependency>

<dependency>
    <groupId>io.github.uncaughterrol</groupId>
    <artifactId>commons-utils</artifactId>
    <version>0.6.0</version>
</dependency>

Gradle

implementation 'io.github.uncaughterrol:commons-security:0.6.0'
implementation 'io.github.uncaughterrol:commons-exception:0.6.0'
implementation 'io.github.uncaughterrol:commons-model:0.6.0'
implementation 'io.github.uncaughterrol:commons-utils:0.6.0'

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Module Details

commons-security

HMAC-SHA256 request signing and verification.

Map<String, String> payload = Map.of(
        "userId", "42",
        "action", "transfer"
);

// Sign
String signature = SignatureSigner.sign(payload, "my-secret-key");

// Verify
boolean valid = SignatureSigner.verify(payload, signature, "my-secret-key");

→ Full documentation

commons-exception

Standardized API exceptions & factory.

// 404 Not Found
throw ExceptionFactory.notFound("User", 42);

// 409 Conflict
throw ExceptionFactory.alreadyExists("User", "email", "john@example.com");

// 500 Internal Error
throw ExceptionFactory.internal("Connection failed", databaseError);

→ Full documentation

commons-model

API response wrappers and invalid parameter models.

// Success response with payload
ApiResponse<UserDto> response = ApiResponse.success(
                "User Created",
                "User was created successfully",
                201,
                userDto
        );

// Error response without invalid params
ApiResponse<Void> response = ApiResponse.error(
        "Not Found",
        "User with id 42 does not exist",
        404
);

// Error response with invalid params (e.g. validation failure)
List<InvalidParam> invalidParams = List.of(
        new InvalidParam("email", "must be a valid email address"),
        new InvalidParam("age", "must be greater than 0")
);

ApiResponse<Void> response = ApiResponse.error(
        "Validation Failed",
        "Request contains invalid parameters",
        400,
        invalidParams
);

→ Full documentation

commons-utils

Utility classes and helper functions shared across commons modules.

Static Utility Usage (SmartStringUtils)

import io.github.uncaughterrol.smartstring.SmartStringUtils;

public class Example {

    public static void main(String[] args) {

        String snake = SmartStringUtils.toSnakeCase("HelloWorldExample");
        System.out.println(snake);
        // hello_world_example

        String camel = SmartStringUtils.toCamelCase("hello_world");
        System.out.println(camel);
        // helloWorld

        String pascal = SmartStringUtils.toPascalCase("hello_world");
        System.out.println(pascal);
        // HelloWorld
    }
}

Pluralization

import io.github.uncaughterrol.smartstring.SmartStringUtils;

public class Example {

    public static void main(String[] args) {

        System.out.println(SmartStringUtils.toPlural("city"));
        // cities

        System.out.println(SmartStringUtils.toPlural("box"));
        // boxes

        System.out.println(SmartStringUtils.toPlural("dog"));
        // dogs
    }
}

Singularization

import io.github.uncaughterrol.smartstring.SmartStringUtils;

public class Example {

    public static void main(String[] args) {

        System.out.println(SmartStringUtils.toSingular("cities"));
        // city

        System.out.println(SmartStringUtils.toSingular("boxes"));
        // box
    }
}

→ Full documentation

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License

MIT License