定义一个 Shape 类用于表示形状，其有一个无参方法area（）法计算形状的面积，返回double类型的结果 -1。 定义 Shape 的子类 Square（正方形） 和 Circle（圆形），重写父类的 area 方法，计算自己的面积，定义double类型的成员变量分别保存正方形的边长和圆形的半径。创建实例时，边长和半径需要通过构造方法传入。 重写 Square（正方形） 和 Circle（圆形）的 toString 方法，返回如下内容： Circle类： Circle: with length of RADIUS is 8.0 Area of the is 201.0619264 Square类： Square: with length of SIDE is 15.0 Area of the is 225.0 在测试类中分别创建3个 Circle 对象和3个 Square 对象，存放在一个 Shape 类型的数组中，使用实现 ShapeComparator 接口的对象作为比较器，通过 Arrays.sort 方法对该数组分别按照图形的面积排序。输出信息验证排序结果。

好的，我已经理解了你的问题。下面是一个可能的实现：

Shape.java：

public abstract class Shape {
    public abstract double area();
}

Square.java：

public class Square extends Shape {
    private double side;

    public Square(double side) {
        this.side = side;
    }

    public double getSide() {
        return side;
    }

    @Override
    public double area() {
        return side * side;
    }

    @Override
    public String toString() {
        return "Square: with length of SIDE is " + side + "\nArea of the is " + area();
    }
}

Circle.java：

public class Circle extends Shape {
    private double radius;

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

    public double getRadius() {
        return radius;
    }

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

    @Override
    public String toString() {
        return "Circle: with length of RADIUS is " + radius + "\nArea of the is " + area();
    }
}

ShapeComparator.java：

import java.util.Comparator;

public class ShapeComparator implements Comparator<Shape> {
    @Override
    public int compare(Shape o1, Shape o2) {
        if (o1.area() < o2.area()) {
            return -1;
        } else if (o1.area() > o2.area()) {
            return 1;
        } else {
            return 0;
        }
    }
}

Test.java：

import java.util.Arrays;

public class Test {
    public static void main(String[] args) {
        Shape[] shapes = new Shape[6];
        shapes[0] = new Circle(8.0);
        shapes[1] = new Circle(5.0);
        shapes[2] = new Circle(10.0);
        shapes[3] = new Square(15.0);
        shapes[4] = new Square(12.0);
        shapes[5] = new Square(20.0);

        Arrays.sort(shapes, new ShapeComparator());

        for (Shape shape : shapes) {
            System.out.println(shape.toString());
        }
    }
}

输出结果应该为：

Square: with length of SIDE is 12.0
Area of the is 144.0
Square: with length of SIDE is 15.0
Area of the is 225.0
Square: with length of SIDE is 20.0
Area of the is 400.0
Circle: with length of RADIUS is 5.0
Area of the is 78.53981633974483
Circle: with length of RADIUS is 8.0
Area of the is 201.06192982974676
Circle: with length of RADIUS is 10.0
Area of the is 314.1592653589793