Java Style Guide¶

Status: 🟢 Active  |  Owner: Java Guild

Base Standard¶

Google Java Style Guide is the base standard with the following enterprise overrides.

Enterprise Overrides¶

Key Rules¶

Immutability¶

• Prefer immutable value objects. Use Java record for value types (Java 16+).
• Mark fields final wherever possible.
• Use unmodifiable collections: List.of(), Map.of(), Collections.unmodifiableList().

Optionals¶

• Use Optional<T> only as a method return type — never as a field or parameter.
• Never call .get() without .isPresent() check — use .orElse(), .orElseThrow(), or .ifPresent().

Modern Java Features (Required for Java 21)¶

• Use records for immutable data carriers.
• Use sealed classes for closed type hierarchies.
• Use pattern matching for instanceof — no explicit cast after instanceof.
• Use text blocks for multi-line strings.
• Use switch expressions instead of switch statements where possible.

// ✅ Modern Java 21
sealed interface Shape permits Circle, Rectangle {}
record Circle(double radius) implements Shape {}
record Rectangle(double width, double height) implements Shape {}

double area(Shape shape) {
    return switch (shape) {
        case Circle c -> Math.PI * c.radius() * c.radius();
        case Rectangle r -> r.width() * r.height();
    };
}

Exception Handling¶

• Never catch Exception or Throwable without re-throwing or logging with full context.
• Never swallow exceptions silently.
• Use checked exceptions only for recoverable conditions; use unchecked for programming errors.
• Create domain-specific exceptions (e.g., OrderNotFoundException extends RuntimeException).

Last reviewed: 2025-Q4  |  Owner: Java Guild