What happens when only a few element from a list are from the same interface-CodePudding

Given I have this class:

class Animal
{
void walk() { } 
....
.... //other methods 
}

Coupled with the interface for animals who are able to chew:

interface Chewable {
void chew();
}

and have Reptile class implement this and not Birds (since Birds cannot chew) :

class Reptile extends Animal implements Chewable { }

and in case of Birds:

class Bird extends Animal { }

Here, reptiles and birds are both an interface of Animal.

If I had a case where I have to loop through a list of IAnimals, and call their chew() function, what will happen when there is a bird in the list ?

CodePudding user response：

The class Animal is not implementing the Chewable interface and therefore if you have a List of type Animal containing both Birds and Reptiles it will not have a chew() method. This is because the type Animal only "knows" of its own members and methods.

CodePudding user response：

If you loop through a List of Animal (List), you could only call methods belonging to Animal. Therefore you can not call chew().