使用超类初始化子类对象java [英] Using superclass to initialise a subclass object java

问题描述

SuperClass object = new SubClass();

为什么要使用超类来实例化上面的子类对象？因为我学习实例化对象的唯一方法是：

Why use a superclass to instantiate a subclass object like above? Because the only way i learnt to instantiate an object is to:

SubClass object = new SubClass();

我正在学习java。

推荐答案

您可能有一个方法只接受 SuperClass 的实例。由于 SubClass 是 SuperClass ，您可以使用 SubClass 并将其视为 SuperClass 。

You may have a method that only takes an instance of SuperClass. Since SubClass is a SuperClass, you can use an instance of SubClass and treat it as SuperClass.

工作时使用相同的行为带接口：

The same behavior is used when working with interfaces:

List someList = new ArrayList();

这就是多态的美。它允许您在不破坏代码的其余部分的情况下更改类内部的实现。

That's the beauty of polymorphism. It allows you to change out the implementation of the class' internals without breaking the rest of your code.

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