有没有会的小伙伴解答一下吧

Question

Answer 1

第二题的参考

public interface Shape {
    double area(double len);
}

public class Square implements Shape{
    @Override
    public double area(double len) {
        return len * len;
    }
}

public class Circle implements Shape{
    public static final Double PI = 3.14;
    @Override
    public double area(double r) {
        return PI * r * r;
    }
}

public class TestMain {
    public static void main(String[] args) {
        double len = 2;
        double r = 3;
        System.out.println("正方形的面积为："+new Square().area(len));
        System.out.println("圆形的面积为："+new Circle().area(r));
    }
}

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