Selenium automation testing course with Java- abstraction with interfaces - class 10

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class 10 :-
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Introduction to interfaces in java:-
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An interface in Java is a blueprint of a class. It is used to achieve abstraction and multiple inheritance in Java.

Key Points about Interfaces:
=============================
An interface contains abstract methods (methods without a body).
It may also contain constants (public static final).
A class implements an interface using the implements keyword.
Interfaces help define a contract that implementing classes must follow.

Syntax Example:
===============
interface Animal {
void eat(); // abstract method
void sleep(); // abstract method
}
Implementation:
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class Dog implements Animal {
public void eat() {
System.out.println("Dog eats bones");
}
public void sleep() {
System.out.println("Dog sleeps");
}

Why Use Interfaces?
1.Abstraction - You only define what should be done, not how.
2.Loose Coupling - Implementation details are hidden from the user.
3.Multiple Inheritance - Java does not support multiple inheritance with classes, but 4.does with interfaces.
5.Contract Definition - Ensures implementing classes follow the same structure.

Changes in Java 8 for Interfaces :-
==================================
Java 8 introduced major enhancements to interfaces:
1. Default Methods
You can provide a method body inside an interface using default keyword.
interface MyInterface {
default void show() {
System.out.println("Default method in interface");
}
}
Please be informed that the default methods are Useful when adding new methods to interfaces without breaking existing implementation.

2. Static Methods
Interfaces can now have static methods.
interface MyInterface {
static void display() {
System.out.println("Static method in interface");
}
}
These are not inherited by implementing classes.

3. Functional Interfaces and Lambda Support
A functional interface is an interface with exactly one abstract method.

Used with lambda expressions.
==========================
@FunctionalInterface
interface Calculator {
int operate(int a, int b);
}
Calculator add = (a, b) arrowOperator a + b;
System.out.println(add.operate(5, 3));