「sealed」タグの記事が1件件あります

Java Sealed

2024年3月6日 · 約2分

白い柴犬

After Java 8, the interface of java have become more and more powerful.

(Java 8) Default methods Provide optional functionality to all implementations
(Java 8) Static methods Utility methods that belong to the interface contract itself, CANNOT be overridden. utility functions that don't need instance context
(Java 9) Private methods: keeping internal helper logic hidden from implementers
Constants: Shared Contract Values public static final cannot be overriden
(Java 17) Sealed: Sealed means you can control exactly which classes can implement your interface (or extend your class). closed hierarchy, This enables better pattern matching, safer APIs, and clearer domain modeling!
(Java 8) @FunctionalInterface indicate this interface supports lambda.

Example:

public interface PaymentProcessor {
    // Abstract method - must be implemented
    void processPayment(double amount);
    
    // Default method - optional to override
    default void logTransaction(double amount) {
        System.out.println("Processing payment of: $" + amount);
        // Common logging logic here
    }
    
    // Another default method
    default boolean validateAmount(double amount) {
        return amount > 0 && amount < 10000;
    }
}

public abstract class AbstractPaymentProcessor {
    private int defaultAmount = 500;
    // Abstract method - must be implemented
    void processPayment(double amount);
    
    // Default method - optional to override
    void logTransaction(double amount) {
        System.out.println("Processing payment of: $" + amount);
        // Common logging logic here
    }
    
    // Another default method
    boolean validateAmount(double amount) {
        return amount > 0 && amount < 10000;
    }
}