Java interfeys

Interfeyslar

Java tilida abstraksiyaga erishishning yana bir usuli — interfeyslar.

interface — tanasi bo‘sh bo‘lgan o‘zaro bog‘liq metodlarni guruhlash uchun ishlatiladigan to‘liq "abstrakt sinf":

Misol

// interface
interface Animal {
  public void animalSound(); // interface method (does not have a body)
  public void run(); // interface method (does not have a body)
}

Interfeys metodlariga murojaat qilish uchun interfeys boshqa sinf tomonidan (extends o‘rniga) implements kalit so‘zi yordamida "amalga oshirilishi" (implement — meros olishga o‘xshash) kerak. Interfeys metodining tanasini uni "amalga oshiruvchi" sinf taqdim etadi:

Misol

// Interface
interface Animal {
  public void animalSound(); // interface method (does not have a body)
  public void sleep(); // interface method (does not have a body)
}

// Pig "implements" the Animal interface
class Pig implements Animal {
  public void animalSound() {
    // The body of animalSound() is provided here
    System.out.println("The pig says: wee wee");
  }
  public void sleep() {
    // The body of sleep() is provided here
    System.out.println("Zzz");
  }
}

class Main {
  public static void main(String[] args) {
    Pig myPig = new Pig();  // Create a Pig object
    myPig.animalSound();
    myPig.sleep();
  }
}

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Interfeyslar haqida eslatmalar:

Abstrakt sinflar kabi interfeyslardan ham obyekt yaratish uchun foydalanib bo‘lmaydi (yuqoridagi misolda MyMainClass sinfida "Animal" obyektini yaratib bo‘lmaydi)
Interfeys metodlarining tanasi bo‘lmaydi — tanani "amalga oshiruvchi" sinf taqdim etadi
Interfeysni amalga oshirishda uning barcha metodlarini qayta aniqlashingiz (override) shart
Interfeys metodlari sukut bo‘yicha abstract va public bo‘ladi
Interfeys atributlari sukut bo‘yicha public, static va final bo‘ladi
Interfeysda konstruktor bo‘lishi mumkin emas (chunki undan obyekt yaratib bo‘lmaydi)

Nima uchun va qachon interfeyslardan foydalanish kerak?

1) Xavfsizlikka erishish uchun — ba’zi tafsilotlarni yashirib, obyektning (interfeysning) faqat muhim tafsilotlarini ko‘rsatish.

2) Java "ko‘plab vorislik"ni (multiple inheritance) qo‘llab-quvvatlamaydi (sinf faqat bitta ota sinfdan (superclass) meros olishi mumkin). Biroq bunga interfeyslar yordamida erishish mumkin, chunki sinf bir nechta interfeysni amalga oshira oladi. Eslatma: Bir nechta interfeysni amalga oshirish uchun ularni vergul bilan ajrating (quyidagi misolga qarang).

Bir nechta interfeys

Bir nechta interfeysni amalga oshirish uchun ularni vergul bilan ajrating:

Misol

interface FirstInterface {
  public void myMethod(); // interface method
}

interface SecondInterface {
  public void myOtherMethod(); // interface method
}

class DemoClass implements FirstInterface, SecondInterface {
  public void myMethod() {
    System.out.println("Some text..");
  }
  public void myOtherMethod() {
    System.out.println("Some other text...");
  }
}

class Main {
  public static void main(String[] args) {
    DemoClass myObj = new DemoClass();
    myObj.myMethod();
    myObj.myOtherMethod();
  }
}

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