In this
tutorial we will discuss the difference between overloading and overriding in
Java. If you are new to these terms then refer the following Concepts:
1. Method
overloading in java
2. Method
overriding in java
Overloading vs Overriding in
Java
1. Overloading
happens at compile-time while Overriding happens at runtime:
The binding of overloaded method call to its definition has happens at
compile-time however binding of overridden method call to its definition
happens at runtime.
2. Static
methods can be overloaded which means a class can have more than one static
method of same name. Static methods cannot be overridden, even if you declare a
same static method in child class it has nothing to do with the same method of
parent class.
3. The
most basic difference is that overloading is being done in the same class while
for overriding base and child classes are required. Overriding is all about
giving a specific implementation to the inherited method of parent class.
4. Static
binding is
being used for overloaded methods and dynamic binding is being used for overridden/overriding
methods.
5. Performance:
Overloading gives better performance compared to overriding. The reason is that
the binding of overridden methods is being done at runtime.
6. private
and final methods can be overloaded but they cannot be overridden. It means a
class can have more than one private/final methods of same name but a child
class cannot override the private/final methods of their base class.
7. Return
type of method does not matter in case of method overloading, it can be same or
different. However in case of method overriding the overriding method can have
more specific return type.
8. Argument
list should be different while doing method overloading. Argument list should
be same in method Overriding.
Overloading example
//A class for adding upto 5 numbers
class Sum
{
int add(int n1, int n2)
{
return n1+n2;
}
int add(int n1, int n2, int n3)
{
return n1+n2+n3;
}
int add(int n1, int n2, int n3, int n4)
{
return n1+n2+n3+n4;
}
int add(int n1, int n2, int n3, int n4, int n5)
{
return n1+n2+n3+n4+n5;
}
public static void main(String args[])
{
Sum obj = new Sum();
System.out.println("Sum of two numbers:
"+obj.add(20, 21));
System.out.println("Sum of three numbers:
"+obj.add(20, 21, 22));
System.out.println("Sum of four numbers: "+obj.add(20, 21, 22, 23));
System.out.println("Sum of five numbers:
"+obj.add(20, 21, 22, 23, 24));
}
}
Output:
Sum of
two numbers: 41
Sum of
three numbers: 63
Sum of
four numbers: 86
Sum of
five numbers: 110
Here we
have 4 versions of same method
add.
We are overloading the method add() here.
Overriding example
package
beginnersbook.com;
class CarClass
{
public int speedLimit()
{
return 100;
}
}
class Ford extends CarClass
{
public int speedLimit()
{
return 150;
}
public static void main(String args[])
{
CarClass obj = new Ford();
int num= obj.speedLimit();
System.out.println("Speed Limit is: "+num);
}
}
Output:
Speed Limit is: 150
Here
speedLimit() method of class Ford is overriding the speedLimit()method
of class CarClass.
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