Warning: Undefined array key 0 in /www/wwwroot/w/show/success.php on line 266

Warning: Trying to access array offset on value of type null in /www/wwwroot/w/show/success.php on line 266

Warning: Undefined array key 0 in /www/wwwroot/w/show/success.php on line 266

Warning: Trying to access array offset on value of type null in /www/wwwroot/w/show/success.php on line 266

10.4　抽象类和密封类

**本节视频教学录像：5分钟**

如果说继承是面向对象设计理论的基石，那么抽象理论和方法就是继承理论的顶梁柱。

Warning: Undefined array key 0 in /www/wwwroot/w/show/success.php on line 276

Warning: Trying to access array offset on value of type null in /www/wwwroot/w/show/success.php on line 276

Warning: Undefined array key 0 in /www/wwwroot/w/show/success.php on line 276

Warning: Trying to access array offset on value of type null in /www/wwwroot/w/show/success.php on line 276