# Java Distributions

## Overview

`lighty-java` supports four major Java distributions, each with different characteristics and use cases.

## Temurin (Eclipse Adoptium)

### Characteristics

* **Provider**: Eclipse Adoptium (formerly AdoptOpenJDK)
* **Type**: OpenJDK builds
* **License**: GPLv2 + Classpath Exception
* **Support**: All Java versions (8, 11, 17, 21+)
* **Platforms**: Windows (x64, ARM64), Linux (x64, ARM64), macOS (x64, ARM64)

### API

* **Base URL**: `https://api.adoptium.net/v3/assets/`
* **Query Parameters**:
  * `feature_version`: Java major version (8, 11, 17, 21)
  * `image_type`: JRE or JDK
  * `os`: Operating system
  * `architecture`: CPU architecture
  * `heap_size`: Normal heap
  * `vendor`: eclipse

### Download Sizes

| Version | Windows x64 | Linux x64 | macOS ARM64 |
| ------- | ----------- | --------- | ----------- |
| Java 8  | \~45 MB     | \~43 MB   | N/A         |
| Java 11 | \~100 MB    | \~98 MB   | \~95 MB     |
| Java 17 | \~110 MB    | \~108 MB  | \~105 MB    |
| Java 21 | \~120 MB    | \~118 MB  | \~115 MB    |

### Usage

```rust
use lighty_java::{JavaDistribution, jre_downloader};

let distribution = JavaDistribution::Temurin;
let java_path = jre_downloader::jre_download(
    runtime_dir,
    &distribution,
    &21,
    |_, _| {}
).await?;
```

### When to Use

* General-purpose Minecraft launchers
* Maximum compatibility across all Minecraft versions
* Need for long-term support (LTS) versions
* Widest platform support

## GraalVM

### Characteristics

* **Provider**: Oracle
* **Type**: High-performance JDK with advanced JIT compiler
* **License**: GPLv2 + Classpath Exception (Community Edition)
* **Support**: Java 17, 21+ only
* **Platforms**: Windows (x64), Linux (x64, ARM64), macOS (x64, ARM64)

### Download Source

* **Source**: GitHub Releases
* **Repository**: `graalvm/graalvm-ce-builds`
* **Format**: Direct download URLs from release assets
* **Naming**: `graalvm-jdk-{version}_{os}_{arch}.{ext}`

### Download Sizes

| Version | Windows x64 | Linux x64 | macOS ARM64 |
| ------- | ----------- | --------- | ----------- |
| Java 17 | \~180 MB    | \~175 MB  | \~170 MB    |
| Java 21 | \~190 MB    | \~185 MB  | \~180 MB    |

### Performance

* **JIT Compiler**: Advanced Graal compiler with better optimization
* **Startup Time**: Faster than standard OpenJDK
* **Peak Performance**: 10-20% better than standard JDK
* **Memory Usage**: Lower with G1GC

### Usage

```rust
use lighty_java::{JavaDistribution, jre_downloader};

let distribution = JavaDistribution::GraalVM;
let java_path = jre_downloader::jre_download(
    runtime_dir,
    &distribution,
    &21,
    |_, _| {}
).await?;
```

### When to Use

* Modern Minecraft versions (1.17+)
* Performance-critical applications
* Users with faster internet (larger downloads)
* Development and testing environments

### Limitations

* No Java 8 or 11 support
* Larger download size
* Windows ARM64 not supported

## Zulu (Azul Systems)

### Characteristics

* **Provider**: Azul Systems
* **Type**: TCK-certified OpenJDK builds
* **License**: GPLv2 + Classpath Exception
* **Support**: All Java versions (8, 11, 17, 21+)
* **Platforms**: Windows (x64, ARM64), Linux (x64, ARM64), macOS (x64, ARM64)

### API

* **Base URL**: `https://api.azul.com/metadata/v1/zulu/packages/`
* **Query Parameters**:
  * `java_version`: Major version
  * `os`: Operating system
  * `arch`: Architecture
  * `bundle_type`: JRE or JDK
  * `javafx`: false
  * `release_status`: GA (General Availability)

### Download Sizes

| Version | Windows x64 | Linux x64 | macOS ARM64 |
| ------- | ----------- | --------- | ----------- |
| Java 8  | \~50 MB     | \~48 MB   | N/A         |
| Java 11 | \~105 MB    | \~103 MB  | \~100 MB    |
| Java 17 | \~115 MB    | \~113 MB  | \~110 MB    |
| Java 21 | \~125 MB    | \~123 MB  | \~120 MB    |

### Enterprise Features

* **TCK Certification**: Fully certified OpenJDK builds
* **Support Options**: Commercial support available
* **ARM Support**: Excellent ARM64 optimization
* **Security Updates**: Regular backports of security fixes

### Usage

```rust
use lighty_java::{JavaDistribution, jre_downloader};

let distribution = JavaDistribution::Zulu;
let java_path = jre_downloader::jre_download(
    runtime_dir,
    &distribution,
    &17,
    |_, _| {}
).await?;
```

### When to Use

* Enterprise environments requiring certification
* ARM-based systems (Raspberry Pi, Apple Silicon)
* Need for commercial support
* Regulatory compliance requirements

## Liberica (BellSoft)

### Characteristics

* **Provider**: BellSoft
* **Type**: Lightweight OpenJDK distribution
* **License**: GPLv2 + Classpath Exception
* **Support**: All Java versions (8, 11, 17, 21+)
* **Platforms**: Windows (x64, ARM64), Linux (x64, ARM64), macOS (x64, ARM64)

### API

* **Base URL**: `https://api.foojay.io/disco/v3.0/packages`
* **Query Parameters**:
  * `version`: Java major version
  * `distribution`: liberica
  * `operating_system`: OS name
  * `architecture`: CPU architecture
  * `archive_type`: Archive format
  * `package_type`: JRE

### Download Sizes

| Version | Windows x64 | Linux x64 | macOS ARM64 |
| ------- | ----------- | --------- | ----------- |
| Java 8  | \~40 MB     | \~38 MB   | N/A         |
| Java 11 | \~95 MB     | \~93 MB   | \~90 MB     |
| Java 17 | \~105 MB    | \~103 MB  | \~100 MB    |
| Java 21 | \~115 MB    | \~113 MB  | \~110 MB    |

### Optimization Focus

* **Size**: Smallest download sizes
* **Memory**: Lower memory footprint
* **Embedded**: Optimized for embedded systems
* **JavaFX**: Optional JavaFX bundles available

### Usage

```rust
use lighty_java::{JavaDistribution, jre_downloader};

let distribution = JavaDistribution::Liberica;
let java_path = jre_downloader::jre_download(
    runtime_dir,
    &distribution,
    &11,
    |_, _| {}
).await?;
```

### When to Use

* Resource-constrained systems
* Older hardware with limited disk space
* Slow internet connections
* Embedded or IoT devices

## Distribution Comparison

| Feature                | Temurin  | GraalVM | Zulu     | Liberica |
| ---------------------- | -------- | ------- | -------- | -------- |
| **Java 8 Support**     | ✅        | ❌       | ✅        | ✅        |
| **Java 11 Support**    | ✅        | ❌       | ✅        | ✅        |
| **Java 17 Support**    | ✅        | ✅       | ✅        | ✅        |
| **Java 21 Support**    | ✅        | ✅       | ✅        | ✅        |
| **Windows ARM64**      | ✅        | ❌       | ✅        | ✅        |
| **Performance**        | Standard | High    | Standard | Standard |
| **Download Size**      | Medium   | Large   | Medium   | Small    |
| **TCK Certified**      | ✅        | ✅       | ✅        | ✅        |
| **Commercial Support** | ❌        | ✅       | ✅        | ✅        |

## Version Detection

Automatically select appropriate Java version for Minecraft:

```rust
use lighty_java::runtime::get_jre_version;

// Minecraft 1.20.4 → Java 17
let version = get_jre_version("1.20.4");
assert_eq!(version, 17);

// Minecraft 1.16.5 → Java 8
let version = get_jre_version("1.16.5");
assert_eq!(version, 8);

// Minecraft 1.18.2 → Java 17
let version = get_jre_version("1.18.2");
assert_eq!(version, 17);
```

### Version Requirements

| Minecraft Version | Required Java | Recommended Distribution                         |
| ----------------- | ------------- | ------------------------------------------------ |
| < 1.12            | Java 8        | Temurin (smallest)                               |
| 1.12 - 1.16.5     | Java 8        | Temurin or Liberica                              |
| 1.17 - 1.17.1     | Java 16       | Temurin or GraalVM                               |
| 1.18+             | Java 17       | GraalVM (performance) or Temurin (compatibility) |

## Platform Support Matrix

### Windows

| Distribution | x64 | ARM64 | Notes                 |
| ------------ | --- | ----- | --------------------- |
| Temurin      | ✅   | ✅     | Full support          |
| GraalVM      | ✅   | ❌     | x64 only              |
| Zulu         | ✅   | ✅     | Excellent ARM support |
| Liberica     | ✅   | ✅     | Full support          |

### Linux

| Distribution | x64 | ARM64 | Notes                 |
| ------------ | --- | ----- | --------------------- |
| Temurin      | ✅   | ✅     | Full support          |
| GraalVM      | ✅   | ✅     | Full support          |
| Zulu         | ✅   | ✅     | Best ARM optimization |
| Liberica     | ✅   | ✅     | Full support          |

### macOS

| Distribution | Intel (x64) | Apple Silicon (ARM64) | Notes               |
| ------------ | ----------- | --------------------- | ------------------- |
| Temurin      | ✅           | ✅                     | Full support        |
| GraalVM      | ✅           | ✅                     | Native ARM builds   |
| Zulu         | ✅           | ✅                     | Optimized for M1/M2 |
| Liberica     | ✅           | ✅                     | Full support        |

## See Also

* [Overview](https://hamadi.gitbook.io/lightylauncher/crates/java/docs/overview) - Architecture and design
* [Installation](https://hamadi.gitbook.io/lightylauncher/crates/java/docs/installation) - Download and installation process
* [Examples](https://hamadi.gitbook.io/lightylauncher/crates/java/docs/examples) - Usage examples