用JAVA实现，改写矩形类，使之实现Printable接口，用printItMyWay（）方法将矩形的相关信息（长、宽、周长、面积）打印在屏幕上；改写正方形类，重载 printItMyWay(）方法将正方形的相关信息（边长、周长、面积）打印在屏幕上。

矩形类实现Printable接口：

public class Rectangle implements Printable {
    private double length;
    private double width;
    
    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }
    
    public double getLength() {
        return length;
    }
    
    public void setLength(double length) {
        this.length = length;
    }
    
    public double getWidth() {
        return width;
    }
    
    public void setWidth(double width) {
        this.width = width;
    }
    
    public double getPerimeter() {
        return 2 * (length + width);
    }
    
    public double getArea() {
        return length * width;
    }
    
    @Override
    public void printItMyWay() {
        System.out.println("矩形长为：" + length);
        System.out.println("矩形宽为：" + width);
        System.out.println("矩形周长为：" + getPerimeter());
        System.out.println("矩形面积为：" + getArea());
    }
}

正方形类重载printItMyWay()方法：

public class Square extends Rectangle {
    public Square(double side) {
        super(side, side);
    }
    
    public double getSide() {
        return getLength();
    }
    
    public void setSide(double side) {
        setLength(side);
        setWidth(side);
    }
    
    @Override
    public void printItMyWay() {
        System.out.println("正方形边长为：" + getSide());
        System.out.println("正方形周长为：" + getPerimeter());
        System.out.println("正方形面积为：" + getArea());
    }
}

使用：

public static void main(String[] args) {
    Rectangle rectangle = new Rectangle(3, 4);
    rectangle.printItMyWay();
    
    Square square = new Square(5);
    square.printItMyWay();
}

输出：

矩形长为：3.0
矩形宽为：4.0
矩形周长为：14.0
矩形面积为：12.0
正方形边长为：5.0
正方形周长为：20.0
正方形面积为：25.0