How Java achieve polymorphism

Question

Java follows oops concepts so polymorphism is one of the oops concepts How Java achieve it?

Answer 1

You clearly have never read the book JAVA PRECISELY by Peter Sestoft.

Go to the section on Java Collections (with the interfaces, abstract classes and concrete classes used for Collections), and study the relationships between all of them.

Ask yourself a couple of questions:

What is an interface? What is it used for? Does it have code associated with it? Can an interface inherit from an interface?

What is an abstract class? What is it used for? Does it have code associated with it? Can an abstract class inherit from an interface? Can it inherit from another abstract class? Can it implement an interface?

What is a concrete class? What is it used for? Does it have code associated with it? Can a concrete class inherit from another concrete class? Can it inherit from an interface? How many concrete or abstract classes can it inherit from? How many interfaces can it implement?

Then go through some of the Collection classes in Java, and answer all of the above questions

And write some code that creates a List interface to a concrete LinkedList class, and see how it answers all of the above questions.

But more importantly, write code that uses all of the above concepts.

Write your own interfaces.

Write your own concrete and abstract classes.

Refactor them to move functionality up the hierarchy and assess the effectiveness of the above.

Answer 2

Polymorphism in Java is implemented with the "extends" and "implements" keywords and with overridden methods (same number and datatype of arguments in subclasses). "implements" is used to inherit interfaces (method signatures and static data) from a Java interface, and must be used with a Java interface. "extends" is used to inherit interfaces and behaviors from a Java class. Java classes can only have one superclass but can have multiple interfaces. Overridden methods are the mechanism that allows an appropriate subclass method to be called regardless of the type of object reference. There is some disagreement in the computer science community about whether method overloading (different number of arguments/datatypes in a single class) is considered polymorphic or not.

Answer 3

Poly means many and morphism means form so polymorphism means a form having different behaviour in different situations.

Ex. + Operator behave both addition and string concatenation.

There are two type of polymorphism in Java .

1 static also called overloading

2. Dynamic also called overriding.

Java achieve polymorphism with the use of overloading and overriding.