polymorphism and inheritance

最新推荐文章于 2021-11-17 14:38:24 发布

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本文介绍了Java中的继承概念，包括如何使用extends关键字建立类之间的继承关系，并解释了如何通过super关键字调用父类构造器。此外，还探讨了抽象类与接口的区别，以及多态性的实现方式。

Inheritance

Inheritance is the capability of a class to use properties and methods of another class while adding its own functionalities.Java uses extends to set the relationship between a parent class and a child class.When extending a class, you can reuse the superclass construct with reserved word super.Note that this must comes first in the subclass's construct. Also note that you cannot override final methods, methods in final classes, private methods or static methods.

Object

The Object is the highest super-class of Java. The methods of java include clone() equals() copy(Object src) finalize() getClass() hashCode() notify() notifyAll() toString() wait().
Abstract This keyword means no instance of this class is allowed to be instantiated.

Abstract methods are methods with no body specification.Subclass must provide override implementation for abstract methods. Interface Interfaces are similar to abstract classes but all methods are abstract and all properties are static final.

Polymorphism

override methods:methods that are redefined in inherited or subclass, same signature are used overload methods:methods with same method name but different parameter number or type Polymorphism is the capability of an action or method to do different things upon the object that it's acting upon.