如下给出抽象图形类（Graph）和坐标点类Point。 1)设计其抽象子类二维图形（TwoDGraph），添加计算面积calArea()和周长calPerimeter()两个抽象方法； 2)从TwoDGraph类派生出圆形Circle，增加圆心centerPoint和半径radius属性，增加构造方法； 3)在Circle中重写calArea、calPerimeter和toString()方法 4)从TwoDGraph类派生出长方形Rectangle，增加左上角坐标leftPoint、长length和宽w

idth属性，增加构造方法； 5)在Rectangle中重写calArea、calPerimeter和toString()方法。

代码如下：

abstract class Graph {
    // 抽象方法
    public abstract void draw();
}

class Point {
    private int x;
    private int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    // 省略getter、setter方法
}

abstract class TwoDGraph extends Graph {
    // 增加计算面积和周长的抽象方法
    public abstract double calArea();
    public abstract double calPerimeter();
}

class Circle extends TwoDGraph {
    private Point centerPoint;
    private double radius;

    public Circle(Point centerPoint, double radius) {
        this.centerPoint = centerPoint;
        this.radius = radius;
    }

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

    @Override
    public double calPerimeter() {
        return 2 * Math.PI * radius;
    }

    @Override
    public void draw() {
        // 绘制圆形
    }

    @Override
    public String toString() {
        return "Circle [centerPoint=" + centerPoint + ", radius=" + radius + "]";
    }
}

class Rectangle extends TwoDGraph {
    private Point leftPoint;
    private double length;
    private double width;

    public Rectangle(Point leftPoint, double length, double width) {
        this.leftPoint = leftPoint;
        this.length = length;
        this.width = width;
    }

    @Override
    public double calArea() {
        return length * width;
    }

    @Override
    public double calPerimeter() {
        return 2 * (length + width);
    }

    @Override
    public void draw() {
        // 绘制长方形
    }

    @Override
    public String toString() {
        return "Rectangle [leftPoint=" + leftPoint + ", length=" + length + ", width=" + width + "]";
    }
}