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Polymorphism

Polymorphism

Polymorphism means "Many Forms" - One Object with many behaviors. In other words, ability to appear more than one i.e. to do different things with single object.
It can be implemented by method overloading and method overriding in java.

For eg. : When you press a device it will turn on, when you press it again it will turn off. Similarly in java "+" Plus Operator has polymorphic behavior:
It can perform Arithmetic Operation as well as Concatenation Operation

Types of Polymorphism

  • Static Polymorphism
  • Dynamic Polymorphism


Static Polymorphism also represented as Compile Time Polymorphism and Early Binding Polymorphism.
Static Polymorphism is just a method overloading.
Thus, it is a process of defining more than one functionalities with same name in same class but having different parameter lists (i.e. different no. of parameters list or different parameters type)
Here compiler will figure out which method to call by their parameters at compile time. thus which function has to be executed will be decided at compile time this is why it is known as static polymorphism.

Eg:
      class Time{
public void currentTime(){
System.out.print("What Time Is It?");
}
public void currentTime(int hr, int min){
System.out.println("Time with minutes and hours");
}
public void currentTime(String day){
System.out.println("Time with Day");
}
}

In this example method currentTime is polymorphic in nature having various functionalities.
         
Dynamic Polymorphism is also represented as Run Time Polymorphism and Late Binding Polymorphism.
Dynamic Polymorphism is nothing but a method overriding.
The process of defining more than one functionalities with same name in different class also having same parameters list.
It can be achieved only through inheritance as different classes are required.
Which method has to be executed will be decided at the run-time.

Eg:
      class Time{
public void currentTime(){
System.out.println("What time is it?");
}
}
class Display{
public void currentTime(){
System.out.println("Display Current Time");
}
}


Point To Remember:

  • Overriding is not possible with final and private methods.
  • Same name function with different time will not considered as method overloading
  • Ambiguity can be occurred in case of compatible datatypes of same methods(as shown in below example).
  • For overriding methods must be exactly same in terms of name, parameters, return type.
  • In overriding, method access modifiers must be same or higher than super class method access modifier.

  • Code To differentiate between Overriding and Overloading 
class A {
void get(){
System.out.println("Get method in Class A");
}
}

class B extends A {
void get(){
System.out.println("Get method in Class B");
}
void get(int x) {
System.out.println("Get method with arg. in Class B: "+x);
}
void get(int x, byte y) {
System.out.println(x+y+" int,byte");
}
void get(byte x, int y) {
System.out.println(x+y+" byte,int");
}
}

class Overload_ride {
public static void main(String[] args) {
A a = new A(); //Normal call
a.get();
A b = new B(); //Overridden method call
b.get();
//b.get(9);        -- Cannot called as not available in class A
B c = new B();        //Overloading call
int x=4;
byte y=10;
c.get(5);
c.get(y);
c.get(x,y);
//c.get(10,6);       -- Ambiguity(get confused with their types)
//c.get(x,x);       -- Ambiguity(no method with two int type available)
}
}

Go to above link to execute this code and practice yourself with your own ideas. Happy Learning :)

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