Polymorphism

Question 1

What is Polymorphism?

Answer 1

Poly=many morph=forms

Question 2

Why Polymorphism?

Answer 2

Polymorphism lets programmers sacrifice specificity for generality and treat any number of classes as their lowest common denominator and limited to methods declared in that denominator.

Question 3

What is Dynamic Binding?

Answer 3

Dynamic binding, which is when actual method implementation used is not determined until runtime and in contrast with static binding, in which method gets resolved at compile time

Question 4

Why Declared Type?

Answer 4

declared type keeps things generic and can reference a lot of objects using one generic type

Question 5

Why Actual Type?

Answer 5

Actual type ensures specificity and when defining implementing class, the method can get implemented in any way

Question 6

Inheritance models, which relationship?

Answer 6

Inheritance models “is a” relationship

Interface models “acts as” relationship

Question 7

Is multiple inheritances allowed in java?

Answer 7

No, in java you can only inherit from one superclass due to the diamond problem.

Question 8

Types of polymorphism

Answer 8

In Java polymorphism is mainly divided into two types:

Compile-time Polymorphism
Runtime Polymorphism

Question 9

Compile Time Polymorphism

Answer 9

It is also known as static polymorphism. This type of polymorphism is achieved by function overloading.

Functions can be overloaded by a change in the number of arguments or/and a change in the type of arguments.

Question 10

Runtime Polymorphism

Answer 10

It is also known as Dynamic Method Dispatch. It is a process in which a function call to the overridden method is resolved at Runtime.
This type of polymorphism is achieved by Method Overriding.

Question 11

Runtime Polymorphism (data members)

Answer 11

In Java, we can override methods only, not the variables(data members), so runtime polymorphism cannot be achieved by data members. For example :
class A
{
    int x = 10;
}

// class B
class B extends A
{
    int x = 20;
}

// Driver class
public class Test
{
    public static void main(String args[])
    {
        A a = new B(); // object of type B

        // Data member of class A will be accessed
        System.out.println(a.x); //10
    }
}

Question 12

Static vs Runtime Binding

Answer 12

Static binding is done during compile-time while the dynamic binding is done during run-time.
private, final, and static methods and variables use static binding and bonded by the compiler while overridden methods are bonded during runtime based upon the type of runtime object