Polymorphism in Java can occur at compile-time via method overloading or at run-time via method overriding. Method overloading involves declaring multiple methods with the same name but different parameters within a class. The compiler determines which overloaded method to call based on the number and type of parameters passed. Method overriding occurs when a subclass has a method with the same name and parameters as a method in the parent class. Run-time polymorphism is demonstrated when an object of the subclass is treated as the parent class type and the method call is resolved based on the object's actual type at runtime.

1. Polymorphism
In JAVA
-M Vishnuvardhan,
Dept. of Computer Science,
SSBN Degree College, ATP

2. SSBN Degree College, ATP M Vishnuvardhan
Introduction
Polymorphism is a Greek word which
means one name multiple forms (Ploy –
many & morphism – forms). There are two
type of Polymorphisms.
 Compile Time Polymorphism ( Method
Overloading )
 Run Time Polymorphism. ( Method Overriding )

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Method Overloading
Declaring multiple methods with same
name in a class is called Method overloading
or compile time polymorphism.
Eg:
class A
{
======
void process()
{ --- }
void process( --- )
{--- }
=====
}
Method
overloading

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Rules for Overloading
To overload multiple methods in java any two methods
must satisfy any of the following conditions. Other wise
those methods are not considered as overloaded and also
compile time error is generated
There must be difference number of parameters (OR)
There must be difference in type of parameters
Valid examples
int add(int a, int b) { }
int add(int a, int b, int c) { }
int add(float a, float b) { }
Invalid examples
int add(int a, int b) { }
int add(int x, int y) { }
float add(int a, int b) { }

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Compiler in Action
When ever a method is invoked the java compiler decides and
calls the appropriate method basing on the no of parameters
or the type of parameters. If any two methods have same
signature then ambiguity arises.
int add(int a, int b) { }
int add(int a, int b, int c) { }
int add(float a, float b) { }
Note: return type doesn’t help in deciding the function
int add(int x, int y) { }
float add(int a, int b) { }
add(10,25)
add(10,25,35)
add(25.45,51.20)
add(10,25)
add(10,25)

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Questions

7. SSBN Degree College, ATP M Vishnuvardhan
Questions