extends 构造器演示，基类带参数与不带参数区别

继承基类时若基类为无参数的构造器则子类可不写构造器Drawing extends Art，若基类构造器有参数，则子类必须手动写构造器CarToon extends Drawing，具体看下面例子

 

package test;

import static test_1.PrintDome.*;

public class ExtendsConstructorDemo {

 public static void main(String[] args) {

  // TODO Auto-generated method stub

  CarToon carToon = new CarToon();

  print(carToon);

 }

}

class Art {

  Art(){

  print("Art()");

 }

}

class Drawing extends Art{

 Drawing(int i){//基类构造器无参数，此处构造器可有可无

  print(i+"===>Drawing()");

 }

}

class CarToon extends Drawing{

  CarToon(){//基类构造器有参数，此处必须在子类构造其中使用super声明，负责编译报错

  super(8);

  print("CarToon");

 

 }

 public String toString(){//有趣的函数

  return "End";

 }

}