The Three Amigos: Intermixing Pattern Matching, Records, and Sealed Classes
summary
Java now gives records give ctor/getters/toString/equals/hashCode so simple data holders are immutable and final; sealed permits clause enforces closed hierarchies so only listed subclasses compile and children must be final/sealed/non-sealed; pattern matching upgrades switch into an expression with guarded cases, dominance checks, and deconstruction of record components; combining all three lets the compiler prove exhaustiveness (no default needed) or emit a DefaultMatchException in stray runtime cases; the demo builds buy/sell records + sealed trade and the examples compile and run as shown.
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chapters (11)
- 0:00Introduction to three amigos
- 1:04Records as data carriers
- 15:13Records immutability and usage
- 16:14Sealed classes and interfaces
- 26:12Sealed hierarchy modifiers
- 35:49Pattern matching basics
- 46:30Guards and dominance in pattern matching
- 48:47Compiler trade-offs in pattern matching
- 49:07Interplay of features in practice
- 56:55Records with sealed classes
- 1:00:52Data-oriented programming summary
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