Interfaces

User-defined Interfaces In Java, User-defined Interfaces are interfaces that you create to define a contract that classes must follow. These interfaces allow you to define abstract methods without providing implementations. Classes that implement the interface must provide their own implementations for the abstract methods. Key Points: A user-defined interface can contain abstract methods (methods without implementations) and constants (static final variables). A class that implements a user-defined interface must provide an implementation for all abstract methods in the interface. Multiple interfaces can be implemented by a single class. Example of User-defined Interface: Defining an Interface: interface Animal { void sound(); // Abstract method void move(); // Abstract method } Implementing the Interface in a Class: class Dog implements Animal { @Override public void sound() { System.out.println("Bark"); } @Override public void move() { System.out.println("Dog runs"); } } public class Main { public static void main(String[] args) { Dog dog = new Dog(); dog.sound(); // Output: Bark dog.move(); // Output: Dog runs } } Example of Multiple Interfaces Implementation: interface Animal { void sound(); } interface Mammal { void move(); } class Dog implements Animal, Mammal { @Override public void sound() { System.out.println("Bark"); } @Override public void move() { System.out.println("Dog runs"); } } public class Main { public static void main(String[] args) { Dog dog = new Dog(); dog.sound(); // Output: Bark dog.move(); // Output: Dog runs } } 🔗 Related Notes Packages and Interfaces Access Modifiers Method Overloading Static Keyword Inheritance Types of Inheritance Method Overriding

Build-in Interface In Java, Built-in Interfaces are interfaces that are part of the Java standard library. These interfaces are provided by Java and can be used directly in your applications without needing to define them yourself. Common Built-in Interfaces: Comparable: This interface is used to compare objects for sorting. A class that implements Comparable must provide an implementation for the compareTo() method. Method: int compareTo(T o) Cloneable: This interface is used to indicate that objects of a class can be cloned using the clone() method. ...

Interfaces An interface in Java is a reference type, similar to a class, that can contain only constants, method signatures, default methods, static methods, and nested types. Interfaces define a contract that classes must implement. Key Points: A class can implement multiple interfaces. Interfaces provide a way to achieve abstraction by allowing methods to be declared without providing their implementation. An interface can be used to define common behaviors that multiple classes can share. Example of Defining and Implementing an Interface: Defining an interface: interface Animal { void sound(); } Implementing the interface in a class: class Dog implements Animal { @Override public void sound() { System.out.println("Bark"); } } public class Main { public static void main(String[] args) { Animal dog = new Dog(); dog.sound(); // Output: Bark } } Example with Multiple Interfaces: interface Animal { void sound(); } interface Mammal { void move(); } class Dog implements Animal, Mammal { @Override public void sound() { System.out.println("Bark"); } @Override public void move() { System.out.println("Dog runs"); } } public class Main { public static void main(String[] args) { Dog dog = new Dog(); dog.sound(); // Output: Bark dog.move(); // Output: Dog runs } } 🔗 Related Notes Access Modifiers Method Overloading Static Keyword Inheritance Types of Inheritance Method Overriding