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What are the necessary conditions for the existence of polymorphism and how to implement it?
What are the necessary conditions for the existence of polymorphism and how to implement it?
Three necessary conditions for the existence of polymorphism:
(Recommended tutorial: java introductory tutorial)
1. Inheritance
2. Rewriting
3. The parent class reference points to the subclass object (the parent class reference points to the subclass object)
For example:
Parent p = new Child(); List<Integer> myList=new LinkedList<>();
(Learning video recommendation: java course)
Polymorphic implementation method:
Method 1: Rewriting
Method 2: Interface
Method 3: Abstract classes and abstract methods
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