Java 示例 - 方法覆盖

• 

  简述

  iv>
• 

  问题描述

  如何在子类的继承中使用方法覆盖？
• 

  解决方案

  此示例演示了由具有不同数量和类型参数的子类覆盖方法的方式。

  
  public class Findareas {
     public static void main (String []agrs) {
        Figure f = new Figure(10 , 10);
        Rectangle r = new Rectangle(9 , 5);
        Figure figref;
        figref = f;
        System.out.println("Area is :"+figref.area());
        figref = r;
        System.out.println("Area is :"+figref.area());
     }
  }
  class Figure {
     double dim1;
     double dim2;
     Figure(double a , double b) {
        dim1 = a;
        dim2 = b;
     }
     Double area() {
        System.out.println("Inside area for figure.");
        return(dim1*dim2);
     }
  }
  class Rectangle extends Figure {
     Rectangle(double a, double b) {
        super(a ,b);
     }
     Double area() {
        System.out.println("Inside area for rectangle.");
        return(dim1*dim2);
     }
  }
  

• 

  结果

  上面的代码示例将产生以下结果。

  
  Inside area for figure.
  Area is :100.0
  Inside area for rectangle.
  Area is :45.0