What is record reflection peculiarities in Java?

In Java, record reflection refers to the ability to examine and manipulate record types at runtime using Java Reflection API. Records, introduced in Java 14 as a preview feature and made stable in Java 16, are a special kind of class in Java that act as transparent carriers for immutable data. Reflection allows developers to inspect the structure of the record, including field names, types, and values, as well as invoke methods dynamically. However, there are some peculiarities when working with records through reflection.

One key point is that records in Java are implicitly final and cannot be subclassed. Additionally, the fields of a record are final and can only be assigned a value once, which can impact how reflection is used for modifying them. Accessing the components of a record is straightforward, but changing them requires careful consideration of their immutable nature.

Example of Using Reflection with a Record

// Example code for inspecting a record using reflection public record Person(String name, int age) {} public class RecordReflectionExample { public static void main(String[] args) throws Exception { Person person = new Person("Alice", 30); // Getting the class of the record Class> recordClass = person.getClass(); // Accessing fields System.out.println("Record Name: " + recordClass.getDeclaredField("name").get(person)); System.out.println("Record Age: " + recordClass.getDeclaredField("age").get(person)); // Getting all components of the record for (var field : recordClass.getDeclaredFields()) { System.out.println("Field: " + field.getName() + ", Type: " + field.getType()); } } }

Java record reflection Java Reflection API immutable data Java records record components Java programming

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