Java 21’s Record Patterns: Practical Performance & Code Clarity Improvements

Java 21 introduces record patterns, a significant enhancement to the Java language that improves both code clarity and, in some cases, performance. This post explores these improvements with practical examples.

Enhanced Code Readability with Nested Record Patterns

Before record patterns, extracting data from nested objects often involved verbose code with multiple get calls. Record patterns streamline this process considerably, leading to more concise and readable code.

Consider a scenario with a User record containing an Address record:

record User(String name, Address address) {}
record Address(String street, String city) {}

Previously, accessing the city would require:

String city = user.address().city();

With record patterns, this becomes:

var (name, (street, city)) = user;

This elegantly extracts the city directly, improving readability and reducing the chance of errors from chained method calls.

Handling Multiple Cases with Pattern Matching

Record patterns shine when dealing with multiple potential structures. Imagine extending the User record to include an optional PhoneNumber:

record User(String name, Address address, PhoneNumber phoneNumber) {}
record PhoneNumber(String number) {}

Without record patterns, checking for the presence of a phone number might involve if statements and null checks. With record patterns, we can write a more elegant and concise solution:

String phoneNumber = switch (user) {
    case (var name, var address, var phoneNumber) -> phoneNumber.number();
    case (var name, var address) -> "No phone number provided";
    default -> throw new IllegalStateException("Unexpected value: " + user);
};

This switch expression neatly handles both cases, improving both readability and maintainability.

Performance Implications

While record patterns primarily enhance code clarity, they can also indirectly lead to performance improvements. By reducing the amount of boilerplate code and simplifying data access, there’s less overhead from method invocations. This is especially noticeable when dealing with deeply nested structures.

However, it’s crucial to note that record patterns themselves don’t provide any inherent speed boost. The performance gain comes from the simplified code structure and the potential reduction in intermediate objects.

Conclusion

Java 21’s record patterns provide a powerful mechanism for improving both the readability and, indirectly, the performance of your Java code. They enable more concise and expressive code, particularly when handling complex data structures and multiple cases. While not a direct performance enhancement in themselves, they indirectly contribute to better performance by simplifying code and reducing overhead. By adopting record patterns, developers can write cleaner, more maintainable, and potentially faster Java code. Integrating them into your projects offers a significant step toward improved code quality and efficiency.