用Java写出创建Shape(图形)抽象类，该类中有一个计算面积的抽象方法getArea（）和属性name。圆形（Circle）和矩形（Rectangle）都继承自图形类。输出图形和矩形的面积，新建测试类输入数据并输出结果

抽象类 Shape 的代码：

public abstract class Shape {
    protected String name;

    public Shape(String name) {
        this.name = name;
    }

    public abstract double getArea();
}

圆形类 Circle 的代码：

public class Circle extends Shape {
    private double radius;

    public Circle(String name, double radius) {
        super(name);
        this.radius = radius;
    }

    @Override
    public double getArea() {
        return Math.PI * radius * radius;
    }
}

矩形类 Rectangle 的代码：

public class Rectangle extends Shape {
    private double width;
    private double height;

    public Rectangle(String name, double width, double height) {
        super(name);
        this.width = width;
        this.height = height;
    }

    @Override
    public double getArea() {
        return width * height;
    }
}

测试类的代码：

public class Test {
    public static void main(String[] args) {
        Circle circle = new Circle("圆形", 5);
        Rectangle rectangle = new Rectangle("矩形", 3, 4);

        System.out.println(circle.name + "的面积是：" + circle.getArea());
        System.out.println(rectangle.name + "的面积是：" + rectangle.getArea());
    }
}

输出结果：

圆形的面积是：78.53981633974483
矩形的面积是：12.0