🚀 R for Maven

Type-safe hierarchical resource access for Java Maven projects - inspired by Android's R.java!

Generate a type-safe, hierarchical R.java class that mirrors your resource directory structure. Access files and folders with intuitive syntax like R.config.database.readContent() while enjoying full IDE autocompletion and compile-time validation.

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✨ Features

• 📁 Hierarchical Structure - Mirrors your resources directory tree
• 🏗️ Build Integration - Generates during Maven compilation
• 🔤 Smart Naming - Converts file/folder names to camelCase Java identifiers
• 📂 Folder Methods - Access folder methods with R.myFolder._self
• ⚡ Fast Generation - Lightweight and efficient

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📦 Installation

Add the plugin to your pom.xml:

<dependencies>
    <!-- Required: the R class use various dependancy such as org.jetbrains.annotations -->
    <dependency>
        <groupId>com.enosistudio</groupId>
        <artifactId>r-for-maven</artifactId>
        <version>latest</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>com.enosistudio</groupId>
            <artifactId>r-for-maven</artifactId>
            <version>latest</version>
            <configuration>
                <keepInProjectFiles>true</keepInProjectFiles> <!-- Optional: keep generated files in project -->
                <resourcesDir>${project.basedir}/src/main/resources</resourcesDir> <!-- Optional: specify resources directory -->
                <outputSrcDirectory>${project.basedir}/src/main/java</outputSrcDirectory> <!-- Optional: specify output source directory -->
                <outputTargetDirectory>${project.build.directory}/generated-sources</outputTargetDirectory> <!-- Optional: specify output target directory -->
                <packageName>com.enosistudio.generated</packageName> <!-- Optional: specify package name -->
            </configuration>
            <executions>
                <execution>
                    <phase>generate-sources</phase> <!-- Optional: Can help intellij to not bug when creating the source folder, when using <keepInProjectFiles>false</keepInProjectFiles> -->
                    <goals>
                        <goal>generate</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

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🏃‍♂️ Usage

Before (❌ Error-prone)

// Hardcoded strings everywhere!
InputStream config = getClass().getResourceAsStream("/config/database.properties");
InputStream logo = getClass().getResourceAsStream("/images/icons/logo.png");

// Typos cause runtime errors 💥
String content = Files.readString(Paths.get("config/databse.properties")); // Whoops!

After (✅ Type-safe & Intuitive)

import com.enosistudio.generated.R;

// Hierarchical access with autocompletion!
String content = R.config.databaseProperties.readContent();
InputStream logo = R.images.icons.logoPng.openStream();
URL resource = R.templates.emailHtml.getURL();

// Folder information
String folderName = R.config._self.getName();

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📂 Generated Structure

Your Resources:

src/main/resources/
├── config/
│   ├── database.properties
│   └── app-settings.yml
├── templates/
│   ├── email.html
│   └── reports/
│       └── invoice.pdf
└── logo.png

Generated R.java:

package com.enosistudio.generated;

public final class R {
    public static final RFile logoPng = new RFile("logo.png");
    
    public static final class config extends RFolder {
        public static final RFolder _self = new config();
        private config() { super("config"); }
        
        public static final RFile databaseProperties = new RFile("config/database.properties");
        public static final RFile appSettingsYml = new RFile("config/app-settings.yml");
    }
    
    public static final class templates extends RFolder {
        public static final RFolder _self = new templates();
        private templates() { super("templates"); }
        
        public static final RFile emailHtml = new RFile("templates/email.html");
        
        public static final class reports extends RFolder {
            public static final RFolder _self = new reports();
            private reports() { super("templates/reports"); }
            
            public static final RFile invoicePdf = new RFile("templates/reports/invoice.pdf");
        }
    }
}

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⚙️ Configuration

Parameter	Default	Description
keepInProjectFiles	true	Keep generated files in src/main/java
resourcesDir	src/main/resources	Resources directory to scan
packageName	com.enosistudio.generated	Package for generated R.java
outputSrcDirectory	src/main/java	Output when keepInProjectFiles=true
outputTargetDirectory	target/generated-sources	Output when keepInProjectFiles=false

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🔧 Requirements

• ☕ Java 17+
• 🔨 Maven 3.6+

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📙 Other

Why no File or Path conversion methods?

Resources should never be manipulated as File or Path objects. Here's why:

• JAR resources are not files - They exist as compressed entries within an archive
• No filesystem access - Resources in JARs have no valid file path
• Read-only nature - Resources cannot be modified at runtime
• Performance overhead - Converting to temp files wastes disk space and memory

Exception: If a legacy library absolutely requires a File object, you must manually copy the resource to a temporary file. However, this should be a last resort, not the default behavior.

For this reason, I don't plan to add any methods related to java.io.File or java.nio.file.Path objects.

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🤝 Contributing

• ☕ Buy me a coffee
• ⭐ If you find this project helpful, please give it a star — it really helps!

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