我在这个java程序中犯了什么错误吗

Question

为什么这个java接口和抽象程序不起作用，我花了几乎一天的时间，但找不到任何答案。有人可以帮忙吗？ 我正在学习java中的面向对象编程。 java 文件名为 Main.java 这是错误 - 错误：在类中找不到 main(String[]) 方法：Camera

// Interface for a smartphone camera
 interface Camera {
    void takePhoto();
}

// Interface for a smartphone media player
 interface MediaPlayer {
    void playMusic();
}

// Parent class for cell phones
class CellPhone {
    String brand;

    public CellPhone(String brand) {
        this.brand = brand;
    }

    void makeCall(String number) {
        System.out.println("Calling " + number + " with " + brand + " phone.");
    }
}

// SmartPhone class extending CellPhone and implementing Camera and MediaPlayer
// interfaces
class SmartPhone extends CellPhone implements Camera, MediaPlayer {
    SmartPhone(String brand) {
        super(brand);
    }

    @Override
    public void takePhoto() {
        System.out.println("Taking a photo with " + brand + " smartphone.");
    }

    @Override
    public void playMusic() {
        System.out.println("Playing music on " + brand + " smartphone.");
    }
}

public class Main {
    public static void main(String[] args) {
        SmartPhone Lava = new SmartPhone("Lava");

        Lava.makeCall("123-456-7890");
        Lava.takePhoto();
        Lava.playMusic();
    }
}