public class MyViewModel extends ViewModel {
    private MutableLiveData<List<User>> users = new MutableLiveData<>();

    public LiveData<List<User>> getUsers() {
        if (users.getValue() == null) {
            loadUsers();
        }
        return users;
    }

    private void loadUsers() {
        // Загрузка пользователей из репозитория или сети
        userRepository.getUsers(new DataLoadCallback() {
            @Override
            public void onDataLoaded(List<User> usersData) {
                users.setValue(usersData);
            }
        });
    }
}

interface Animal {
    void eat();
}

abstract class Mammal {
    abstract void breathe();
    void sleep() {
        System.out.println("Sleeping");
    }
}

class Dog extends Mammal implements Animal {
    @Override
    public void eat() {
        System.out.println("Dog is eating");
    }

    @Override
    void breathe() {
        System.out.println("Dog is breathing");
    }
}

class Engine {
    void start() {
        System.out.println("Двигатель запущен.");
    }
}

class Wheel {
    void rotate() {
        System.out.println("Колесо вращается.");
    }
}

class Car {
    private Engine engine = new Engine();
    private Wheel[] wheels = { new Wheel(), new Wheel(), new Wheel(), new Wheel() };

    void start() {
        engine.start();
        for (Wheel wheel : wheels) {
            wheel.rotate();
        }
        System.out.println("Автомобиль поехал.");
    }
}

public class Main {
    public static void main(String[] args) {
        Car car = new Car();
        car.start();
    }
}

import kotlinx.coroutines.*

fun main() = runBlocking<Unit> {
    launch(Dispatchers.Main) {
        // Обновление пользовательского интерфейса
        println("Main thread: ${Thread.currentThread().name}")
    }
    launch(Dispatchers.IO) {
        // Задача ввода-вывода
        println("IO thread: ${Thread.currentThread().name}")
    }
    launch(Dispatchers.Default) {
        // Тяжелая вычислительная задача
        println("Default thread: ${Thread.currentThread().name}")
    }
}

public class FragmentExample extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_example, container, false);
    }
}

<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
       

 android:layout_height="wrap_content"
        android:text="Hello Fragment!"
        android:gravity="center" />
</LinearLayout>

public class MyClass {
    public int publicVar = 1;
    protected int protectedVar = 2;
    int packagePrivateVar = 3; // default, no modifier
    private int privateVar = 4;
}

class MyClass {
    var publicVar = 1 // по умолчанию public
    protected var protectedVar = 2
    internal var internalVar = 3
    private var privateVar = 4
}

abstract class Animal {
    abstract void makeSound();

    void breathe() {
        System.out.println("I am breathing.");
    }
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Bark");
    }
}

public class Test {
    public static void main(String[] args) {
        Animal myDog = new Dog();
        myDog.makeSound();  // Выводит: Bark
        myDog.breathe();    // Выводит: I am breathing.
    }
}