用java运行卡车要装载一批货物，货物有三种商品：电视、计算机和洗衣机。需要计算出大货车承载的3种货物的重量。要求有一个ComputeWeight接口，该接口中有一个抽象方法： public double computeWeight(); 设计3个实现接口的类：Television, Computer, WashMachine。这三个类通过实现接口给出自重。 定义一个Car类，该类用ComputeWeight接口类型的数组作为成员，那么该数组的单元可以存放Television, Computer, WashMachine对象的引用。 要求：设计程序能输出Car对象所装载的货物的总重量。

以下是代码实现：

// ComputeWeight接口
interface ComputeWeight {
    double computeWeight();
}

// Television类
class Television implements ComputeWeight {
    private double weight = 50;

    public double computeWeight() {
        return weight;
    }
}

// Computer类
class Computer implements ComputeWeight {
    private double weight = 20;

    public double computeWeight() {
        return weight;
    }
}

// WashMachine类
class WashMachine implements ComputeWeight {
    private double weight = 70;

    public double computeWeight() {
        return weight;
    }
}

// Car类
class Car {
    private ComputeWeight[] goods;

    public Car(ComputeWeight[] goods) {
        this.goods = goods;
    }

    public double getTotalWeight() {
        double total = 0;
        for (ComputeWeight g : goods) {
            total += g.computeWeight();
        }
        return total;
    }
}

// 测试程序
public class Test {
    public static void main(String[] args) {
        ComputeWeight[] goods = new ComputeWeight[3];
        goods[0] = new Television();
        goods[1] = new Computer();
        goods[2] = new WashMachine();

        Car car = new Car(goods);
        System.out.println("Car对象所装载的货物的总重量为：" + car.getTotalWeight() + "kg");
    }
}

运行程序后，会输出：Car对象所装载的货物的总重量为：140.0kg。