implements

Learn to implement an interface with a class.

What is implements?

The implements keyword declares that a class implements an interface. The interface forms a contract for the class; the class must contain all members of the interface. The interface provides only signatures; the implementation belongs to the class.

interface Drivable {
  drive(): void;
}
class Car implements Drivable {
  drive() { console.log("vroom"); }
}

Implementing multiple interfaces

A class can implement multiple interfaces; they are separated by commas. All members of all interfaces must be present in the class. Unlike extends, which is limited to single inheritance, this allows multiple contracts.

interface Walkable { walk(): void; }
interface Flyable { fly(): void; }
class Bird implements Walkable, Flyable {
  walk() {}
  fly() {}
}

Exercise Implement the SesCikariran class

Define interface SesCikariran with sesCikar(): void inside. Then make the Kedi class implement this interface and have sesCikar print "miyav". Put a console.log inside the method and call new Kedi().sesCikar().

Show example solution

interface SesCikariran {
  sesCikar(): void;
}
class Kedi implements SesCikariran {
  sesCikar() { console.log("miyav"); }
}
new Kedi().sesCikar();

Test yourself

What must a class using implements do?
- Must implement all members of the interface
- Must implement only one member
- Must extend the interface
- Must mark the interface as abstract
Show answer

Must implement all members of the interface — implements establishes a contract between the class and the interface; the class must contain all members of the interface.

Keyword to implement an interface

class Araba ____ Surulebilir { sur() {} }

Show answer

class Araba implements Surulebilir { sur() {} }

implements concepts

implements

Applies the interface contract
interface

Contains only signatures
sözleşme

Makes members mandatory
virgül

Separates multiple interfaces

Next lesson: Get and set

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