Polymorphism (computer science): Difference between revisions

Revision as of 14:22, 17 March 2023

Revision as of 12:11, 23 May 2023

Line 89:

In the following Java example we make cats and dogs subtypes of animals. The procedure <code>letsHear()</code> accepts an animal, but will also work correctly if a subtype is passed to it:

<syntaxhighlight lang="Javajava">

abstract class AnimalPet {

abstract String talkspeak();

}

class Cat extends AnimalPet {

String talkspeak() {

return "Meow!";

}

}

class Dog extends AnimalPet {

String talkspeak() {

return "Woof!";

}

}

static void letsHear(final AnimalPet apet) {

println(apet.talkspeak());

}

Line 115:

}

</syntaxhighlight>

[[File:UML class pet.svg]]

In another example, if ''Number'', ''Rational'', and ''Integer'' are types such that ''Number''&nbsp;:&gt;&nbsp;''Rational'' and ''Number''&nbsp;:&gt;&nbsp;''Integer'', a function written to take a ''Number'' will work equally well when passed an ''Integer'' or ''Rational'' as when passed a ''Number''. The actual type of the object can be hidden from clients into a [[Black box (systems)|black box]], and accessed via object [[identity (object-oriented programming)|identity]].