gyugyu90

abstract interface class ToBeImplemented {
  void doSomething();
}

gyugyu90

class Implementation implements MyClass {
  @override
  int _privateInstanceVariable = 0;

  @override
  int instanceVariable = 0;

  @override
  void _privateMethod() {
    // TODO: implement _privateMethod

gyugyu90

class MyClass {
  static final CONSTANT = 1;

  static void staticMethod() {
    print('this is static method');
  }

  int instanceVariable = 2;

  final finalInstanceVariable = 3;

gyugyu90

abstract class Feed {
  void onClick();
}

class PostFeed implements Feed {
  @override
  void onClick() {
    print('show tags');
  }
}

gyugyu90

abstract class Feed {
  void onClick();
}

class PostFeed extends Feed {
  @override
  void onClick() {
    print('show tags');
  }
}

gyugyu90

void main() {
  var headphones = [
    BluetoothHeadphone(),
    Headphone(),
    NoiseCancellingHeadphone()
  ];

  headphones.forEach((headphone) {
    headphone.decreaseVolume();
    print(headphone.volume); // 4.5, 4.0, 4.8

gyugyu90

void main() {
  Headphone bluetoothHeadphone = BluetoothHeadphone();
  
  // bluetoothHeadphone.togglePlay(); // Error: The method 'togglePlay' isn't defined for the class 'Headphone'.
  
  bluetoothHeadphone.increaseVolume();
  print(bluetoothHeadphone.volume); // 5.5
}

gyugyu90

class NoiseCancellingHeadphone extends BluetoothHeadphone {
  bool noiseCancellingEnabled = false;

  @override
  double get volumeUnit => 0.2;

  void toggleNoiseCancelling() {
    noiseCancellingEnabled = !noiseCancellingEnabled;
  }

gyugyu90

class Headphone {
  double volume = 5;
  double volumeUnit = 1;

  void increaseVolume() {
    if (volume == 10) {
      print('최고 볼륨입니다!');
      return;
    }

gyugyu90

class BluetoothHeadphone extends Headphone {
  bool isPlaying = false;

  void togglePlay() {
    isPlaying = !isPlaying;
  }

  @override
  void increaseVolume() {
    if (volume == 10) {