class Square extends Rectangle
{
public Square()
{
}
public Square(double x)
{
super(x,x);
}
}
3.定義接口Printable，其中包括壹個方法print ()，這個方法沒有形參，返回值為空
public interface Printable
{
public void print();
}
4.改寫矩形類，使之實現Printable接口，用print ()方法將矩形的相關信息(長、寬、周長、面積)打印在屏幕上
class Rectangle implements Printable{
protected double x;
protected double y;
public Rectangle()
{
x = 0;
y = 0;
}
public Rectangle(double x,double y)
{
this.x = x;
this.y = y;
}
public double getCircle()
{
return 2*(x+y);
}
public double getArea()
{
return x*y;
}
public void setX(double x)
{
this.x = x;
}
public void setY(double y)
{
this.y = y;
}
public void print()
{
System.out.println("矩形的長：" + x + "寬：" + y + "周長：" + getCircle() + "面積：" + getArea());
}
}
5.改寫正方形類，重載print()方法，將正方形的邊長、周長、面積打印在屏幕上
class Square extends Rectangle
{
public Square()
{
}
public Square(double x)
{
super(x,x);
}
public void print()
{
System.out.println("正方形的邊長：" + x + "周長：" + getCircle() + "面積：" + getArea());
}
}
6.將矩形和正方形組織成壹個包mybag
將矩形類和正方形類前再多加壹行
package mybag