Java 8 Features

A structured repository demonstrating the key features introduced in Java 8, implemented through hands-on examples. Each package focuses on one specific concept for clarity and easy navigation.

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Concepts Covered

#	Feature	Package
1	Functional Interfaces	functional_interfaces/
2	Lambda Expressions	lambdas/
3	Built-in Functional Interfaces (Consumer, Predicate)	functional_interfaces/
4	Interface Inheritance & Non-Functional Interfaces	functional_interfaces/
5	Default & Static Methods in Interfaces	default_methods/
6	Multithreading with Lambda (Runnable)	lambdas/

Concepts in Detail

Functional Interfaces & Lambdas

A Functional Interface is any interface with exactly one abstract method, annotated with @FunctionalInterface. Java 8 allows these to be implemented using lambda expressions instead of verbose anonymous inner classes.

// Traditional way
Interface obj = new Interface() {
    public void incomplete() {
        System.out.println("implemented");
    }
};

// Java 8 Lambda way
Interface obj = () -> System.out.println("implemented");

Interface Inheritance

An interface can extend another interface and still remain a functional interface, as long as it does not add any new abstract methods. Adding even one new abstract method breaks the @FunctionalInterface contract.

Built-in Functional Interfaces

Java 8 ships with ready-to-use functional interfaces in java.util.function:

• Consumer<T> — takes input, returns nothing
• Predicate<T> — takes input, returns boolean
• Function<T, R> — takes input, returns a result
• Supplier<T> — no input, returns a result

Multithreading with Lambda

Java 8 lambdas simplify thread creation by allowing Runnable to be expressed as a single-line lambda, eliminating the need to create a separate class.

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