Interface In Dart

Interface In Dart :

• Class implements interface then it must override every method and instance variable of interface.
• Dart does not have a syntax for declaring interfaces. The class declaration is themselves interface in a dart.

 class Framework{ void kotlin() {
 print("kotiln is good lanaguge");
 } void flutter() {
 print("Flutter next generation lanaguge");
 }
 }
 class Android implements Framework { @override
 void kotlin() {
 print("call kotlin");
 } @override
 void flutter() {
 print("call flutter");
 }
 }
main() {
   Framework framework = new Framework();
   Android android = new Android();
framework.kotlin();
   framework.flutter();
android.kotlin();
   android.flutter();
 }

output :

kotiln is good lanaguge
Flutter next generation lanaguge
call kotlin
call flutter

Real time example interface :

class ButtonClickListener {
  void onButtonClick() {
    print("Default Button Clicked !!");
  }
}

class Login implements ButtonClickListener {
  // implement all the methods of  ButtonClickListener
  onButtonClick() {
    print("Login Button Clicked !!");
  }
}

class Signup implements ButtonClickListener {
  // implement all the methods of  ButtonClickListener
  onButtonClick() {
    print("Signup Button Clicked !!");
  }
}

void main() {
  // you can create an object of a class which act as implicit interface
  ButtonClickListener listener = new ButtonClickListener();
  listener.onButtonClick();
  Login login = new Login();
  login.onButtonClick();
  Signup signUp = new Signup();
  signUp.onButtonClick();
}

Multiple Interface :

Dart does not support multiple inheritance but dart can implement multiple interfaces.

Syntax :
class class_name implements interface1, interface2, interface3

class Person {
  String name;

  void showName() {
    print("My name is $name");
  }

  void walk() {
    print("Persxon can walk");
  }

  void talk() {
    print("Person can talk");
  }
}

class Kamlesh {
  String profession;

  void showProfession() {
    print("from class kamlesh my profession is $profession");
  }
}

class Jay implements Person, Kamlesh {
  @override
  String profession;

  @override
  void showProfession() {
    print("from class Jay my Profession is $profession");
  }

  @override
  String name;

  @override
  void showName() {
    print("From class Jay my name is $name");
  }

  @override
  void walk() {
    print("Jay can walk");
  }

  @override
  void talk() {
    print("Jay can talk");
  }
}

main() {
  Person person = new Person();
  Jay  jay.name = "JAY";
  jay = new Jay();
  Kamlesh kamlesh = new Kamlesh();

  person.walk();
  person.talk();
  person.name = "Person";
  person.showName();

  print("");

  jay.walk();
  jay.talk();
  jay.profession = "Chemical Engineer";
  kamlesh.showProfession();
  jay.showName();

  print("");

  kamlesh.profession = "Software Development";
  kamlesh.showProfession();
}

Output :

Person can walk
Person can talk
My name is Person

Jay can walk
Jay can talk
from class kamlesh my profession is null
From class Jay my name is JAY

from class kamlesh my profession is Software Development

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