public class  Test {     public static void main(String[] args)      {         Sequare s = new Sequare(12);         System.out.println("正方形的面积是:" + s.area(s.getBian()));         Circle c  = new Circle(15);         System.out.println("圆的面积是:" + c.area(c.getRadius()));     } } interface Shape {     double area(double data); } class Sequare implements Shape {     private double bian;     public Sequare(double bian)     {         this.bian = bian;     }     public double getBian()     {         return bian;     }     public double area(double data)     {         return data*data;     } } class Circle implements Shape {     private double radius;     public Circle(double radius)     {         this.radius = radius;     }     public double getRadius()     {         return radius;     }     public double area(double data)     {         return data*data*Math.PI;     } }