组合两个对象(java)

// Engine类
public class Engine {
    private String type;

    public Engine(String type) {
        this.type = type;
    }

    public void start() {
        System.out.println("Engine of type " + type + " started.");
    }
}

// Car类
public class Car {
    private Engine engine;

    public Car(Engine engine) {
        this.engine = engine;
    }

    public void startCar() {
        engine.start();
        System.out.println("Car started.");
    }
}

// 测试类
public class Test {
    public static void main(String[] args) {
        Engine petrolEngine = new Engine("Petrol");
        Car myCar = new Car(petrolEngine);
        myCar.startCar();
    }
}

public interface EngineInterface {
    void start();
    void stop();
}

public class Engine implements EngineInterface {
    // 实现接口方法
}

public class Car {
    private EngineInterface engine;

    public Car(EngineInterface engine) {
        this.engine = engine;
    }

    // 使用接口方法
}