chapter09_01.java

适合于初学者使用的许多经典的实例

//--------------------------------------------调用父类中的构造函数-------------------------------------------------//

class C_01Circle {
	     private double pi =3.1415926;
	     private double radius;
	     
	     public C_01Circle() {
	     	     System.out.println("C_01Circle constructor called !!");
	     }
	     
	     public C_01Circle(double r) {                                 // 有参数的构造函数--------------------------------
	     	     System.out.println("C_01Circle(double r) constructor called !!");
	     	     radius=r;
	     }
	     
	     public void show() {
	     	     System.out.println("Area="+pi*radius*radius);
	     }
}


class C_01Coin extends C_01Circle {                  // 定义 C_01Coin 类，继承自类 C_01Circle()------------------
	     private int value;
	     public C_01Coin() {
	     	     System.out.println("C_01Coin() constructor called !!");
	     }
	     
	     public C_01Coin(double r,int v) {
	     	     super(r);                                                 // 调用父类里，有参数的构造函数-----------------------
	     	     value=v;
	     	     System.out.println("C_01Coin(double r,int v) constructor called !!");
	     }
}


public class Chapter09_01 {
         public static void main(String[] args) {
         	     C_01Coin coin01=new C_01Coin();                        // 创建对象，并调用没有参数的构造函数----------
         	     C_01Coin coin02=new C_01Coin(3.6,100);                // 创建对象并调用，有两个参数的 构造函数--------
         	     coin01.show();
         	     coin02.show();
         }
}