Method Overloading in Java with examples

Method Overloading in Java with examples

Method Overloading is a feature that allows a class to have two or more methods having same name, if their argument lists are different. In the last tutorial, we discussed constructor overloading that allows a class to have more than one constructors having different argument lists.

Argument lists could differ in –

1. Number of parameters.

2. Data type of parameters.

3. Sequence of Data type of parameters.

Method overloading is also known as Static Polymorphism.

Points to Note:

1. Static Polymorphism is also known as compile time binding or early binding.

2. Static binding happens at compile time. Method overloading is an example of static binding where binding of method call to its definition happens at Compile time.

Method Overloading examples:

As discussed above, method overloading can be done by having different argument list. Let’s see examples of each and every case.

Example 1: Overloading – Different Number of parameters in argument list

When methods name is same but number of arguments are different.

               

In the above example – method disp() has been overloaded based on the number of arguments – We have two definition of method disp(), one with one argument and another with two arguments.

Example 2: Overloading – Difference in data type of arguments

In this example, method disp() is overloaded based on the data type of arguments – Like example 1 here also, we have two definition of method disp(), one with char argument and another with int argument.

               

Example3: Overloading – Sequence of data type of arguments

Here method disp() is overloaded based on sequence of data type of arguments – Both the methods have different sequence of data type in argument list. First method is having argument list as (char, int) and second is having (int, char). Since the sequence is different, the method can be overloaded without any issues.

               

Let’s see few Valid/invalid cases of method overloading

Case 1: 

Result: Compile time error. Argument lists are exactly same. Both methods are having same number, data types and same sequence of data types in arguments.

Case 2:

Result: Perfectly fine. Valid case for overloading. Here data types of arguments are different.

Case 3:

               

Result: Perfectly fine. Valid case for overloading. Here number of arguments are different.

Case 4:

Result: Perfectly fine. Valid case for overloading. Sequence of the data types are different, first method is having (int, float) and second is having (float, int).

Case 5:

Result: Compile time error. Argument lists are exactly same. Even though return type of methods are different, it is not a valid case. Since return type of method doesn’t matter while overloading a method.

Guess the answers before checking it at the end of programs:

Question 1 – return type, method name and argument list same.

               

Answer:

It will throw a compilation error: More than one method with same name and argument list cannot be defined in a same class.

Question 2 – return type is different. Method name & argument list same.

               

Answer:
It will throw a compilation error: More than one method with same name and argument list cannot be given in a class even though their return type is different. Method return type doesn’t matter in case of overloading.