Chapter 5. Pattern Matching

Pattern matching transforms how Java handles type checking, casting, and data extraction by combining these operations into single, expressive constructs. This modern feature reduces boilerplate code while improving type safety and readability.

Key Topics

This chapter explores pattern matching across different contexts and use cases:

• Pattern Variables in instanceof: Test and bind types in one step, eliminating manual casting
• Type Patterns in Switch: Match on types with exhaustiveness checking for sealed hierarchies
• Guard Clauses: Add conditional logic to patterns using the when keyword
• Record Patterns: Destructure nested records directly in pattern matching expressions
• Sealed Types Integration: Leverage compile-time exhaustiveness verification for maintainable code

Pattern matching represents a fundamental shift in Java's approach to polymorphic code, making it more concise and type-safe while maintaining the language's strong compile-time guarantees.