Default aur Static Methods in Interface

title: Default and Static Methods in Interface description: Java 8 mein interface ke default aur static methods

Java 8 se interfaces mein concrete methods add ho sakte hain — backward compatibility ke liye.

Default Method

java exampleWoHoTech

interface Vehicle {
    void start();  // Abstract

    // Default method — implementation hai
    default void stop() {
        System.out.println("Vehicle ruk gayi");
    }

    default void fuelUp() {
        System.out.println("Fuel bhara ja raha hai");
    }
}

class Car implements Vehicle {
    @Override
    public void start() { System.out.println("Car start hui"); }

    // stop() override nahi kiya — Vehicle ka default use hoga
    // fuelUp() override kiya
    @Override
    public void fuelUp() {
        System.out.println("Car mein petrol bhara");
    }
}

Car c = new Car();
c.start();   // "Car start hui"
c.stop();    // "Vehicle ruk gayi" (default)
c.fuelUp();  // "Car mein petrol bhara" (overridden)

Diamond Problem Resolution

java exampleWoHoTech

interface A { default void hello() { System.out.println("A"); } }
interface B { default void hello() { System.out.println("B"); } }

class C implements A, B {
    @Override
    public void hello() {
        A.super.hello(); // Explicitly choose A's version
        B.super.hello(); // Or B's version
    }
}

Static Method

java exampleWoHoTech

interface MathUtils {
    static int square(int n) { return n * n; }
    static int cube(int n) { return n * n * n; }
    static boolean isPositive(int n) { return n > 0; }
}

// Interface name se call karo
MathUtils.square(5);     // 25
MathUtils.isPositive(3); // true

Kyun Add Kiya Gaya?

Existing interfaces mein methods add karna — implementing classes tod nahi jaaye
Utility methods interface ke paas rakhna
Collection interfaces mein forEach, stream, removeIf etc. add kiya gaya

title: Default and Static Methods in Interface description: Java 8 mein interface ke default aur static methods

Java 8 se interfaces mein concrete methods add ho sakte hain — backward compatibility ke liye.

Default Method

java exampleWoHoTech

interface Vehicle {
    void start();  // Abstract

    // Default method — implementation hai
    default void stop() {
        System.out.println("Vehicle ruk gayi");
    }

    default void fuelUp() {
        System.out.println("Fuel bhara ja raha hai");
    }
}

class Car implements Vehicle {
    @Override
    public void start() { System.out.println("Car start hui"); }

    // stop() override nahi kiya — Vehicle ka default use hoga
    // fuelUp() override kiya
    @Override
    public void fuelUp() {
        System.out.println("Car mein petrol bhara");
    }
}

Car c = new Car();
c.start();   // "Car start hui"
c.stop();    // "Vehicle ruk gayi" (default)
c.fuelUp();  // "Car mein petrol bhara" (overridden)

Diamond Problem Resolution

java exampleWoHoTech

interface A { default void hello() { System.out.println("A"); } }
interface B { default void hello() { System.out.println("B"); } }

class C implements A, B {
    @Override
    public void hello() {
        A.super.hello(); // Explicitly choose A's version
        B.super.hello(); // Or B's version
    }
}

Static Method

java exampleWoHoTech

interface MathUtils {
    static int square(int n) { return n * n; }
    static int cube(int n) { return n * n * n; }
    static boolean isPositive(int n) { return n > 0; }
}

// Interface name se call karo
MathUtils.square(5);     // 25
MathUtils.isPositive(3); // true

Kyun Add Kiya Gaya?

Existing interfaces mein methods add karna — implementing classes tod nahi jaaye
Utility methods interface ke paas rakhna
Collection interfaces mein forEach, stream, removeIf etc. add kiya gaya

Default aur Static Methods in Interface

Default Method

Diamond Problem Resolution

Static Method

Kyun Add Kiya Gaya?

Continue learning this concept

Default aur Static Methods in Interface

Default Method

Diamond Problem Resolution

Static Method

Kyun Add Kiya Gaya?

Continue learning this concept