Java 25 for Hytale

Modern Java features and patterns for Hytale plugin development.

Why Java 25?

Hytale server runs on Java 25 - you must use this version for plugin development.

Installation

Windows (Recommended)

Using winget (Windows Package Manager)

winget install EclipseAdoptium.Temurin.25.JDK

Verify installation

java --version

Manual Download

• Go to Adoptium.net

• Download Temurin 25 (LTS)

• Run installer

• Add to PATH if not automatic

macOS

brew install --cask temurin@25

Linux

Ubuntu/Debian

sudo apt install temurin-25-jdk

Fedora

sudo dnf install temurin-25-jdk

Key Java 25 Features for Hytale

Records (Data Classes)

Perfect for immutable data objects:

// Instead of verbose class with getters/equals/hashCode public record PlayerData(String name, int level, double health) {}

// Usage var data = new PlayerData("Steve", 10, 100.0); System.out.println(data.name()); // "Steve"

Pattern Matching

Cleaner type checks:

// Old way if (obj instanceof Player) { Player player = (Player) obj; player.sendMessage("Hello!"); }

// Java 25 way if (obj instanceof Player player) { player.sendMessage("Hello!"); }

Switch Expressions

String message = switch (gameMode) { case SURVIVAL -> "Good luck surviving!"; case CREATIVE -> "Build freely!"; case ADVENTURE -> "Explore the world!"; default -> "Welcome!"; };

Pattern Matching in Switch

Object entity = getEntity(); String type = switch (entity) { case Player p -> "Player: " + p.getName(); case NPC n -> "NPC: " + n.getType(); case Monster m -> "Monster: " + m.getName(); case null -> "No entity"; default -> "Unknown entity"; };

Sealed Classes

Restrict inheritance:

public sealed class GameEvent permits PlayerEvent, WorldEvent, BlockEvent { // Base event class }

public final class PlayerEvent extends GameEvent { // Cannot be extended further }

Virtual Threads (Project Loom)

Lightweight concurrency for async operations:

// Old way - platform threads are heavy new Thread(() -> loadPlayerData()).start();

// Java 25 way - virtual threads are lightweight Thread.startVirtualThread(() -> loadPlayerData());

// Or with executor try (var executor = Executors.newVirtualThreadPerTaskExecutor()) { executor.submit(() -> loadPlayerData()); executor.submit(() -> loadWorldData()); }

Text Blocks

Multi-line strings:

String json = """ { "name": "MyPlugin", "version": "1.0.0", "author": "YourName" } """;

Hytale-Specific Patterns

Null Safety

Always check for null components:

// Good var health = entity.getComponent(HealthComponent.class); if (health != null) { health.heal(10); }

// Better with Optional entity.getComponentOptional(HealthComponent.class) .ifPresent(h -> h.heal(10));

Functional Event Handling

// Lambda for simple handlers registerEventListener(PlayerJoinEvent.class, e -> e.getPlayer().sendMessage("Welcome!"));

// Method reference for reusable handlers registerEventListener(PlayerJoinEvent.class, this::onPlayerJoin);

private void onPlayerJoin(PlayerJoinEvent event) { // Complex logic here }

Stream API for Collections

// Filter and process players List<Player> onlinePlayers = getServer().getPlayers();

onlinePlayers.stream() .filter(p -> p.getLevel() > 10) .forEach(p -> p.giveReward("veteran_badge"));

// Count specific types long monsterCount = getWorld().getEntities().stream() .filter(e -> e instanceof Monster) .count();

Common Issues

Issue Solution

Wrong Java version Set JAVA_HOME to Java 25

Class not found Check Gradle compileOnly dependency

Unsupported class version Rebuild with Java 25 toolchain

IntelliJ uses wrong JDK Project Structure → SDK → Java 25

IDE Configuration

IntelliJ IDEA

• File → Project Structure → Project

• Set SDK to Java 25

• Set Language Level to 25

Gradle (build.gradle.kts)

java { toolchain { languageVersion.set(JavaLanguageVersion.of(25)) } }