Function in java.

 ■》Methods/Functions->

A function is a block of code that performs a specific task.

■ Why are functions used?

○ If some functionality is performed at multiple places in software, then rather than writing the same code again and again, we create a function and call it everywhere. This helps reduce code redundancy.

○ Functions make maintenance of code easy as      we have to change at one place if we make          future changes to the functionality.

○ Functions make the code more readable and     easy to understand.

■》The syntax for function declaration is :

return-type  function_name (parameter 1, parameter2, …… parameter n){

 //function_body

}

■ return-type->

The return type of a function is the data type of the variable that function returns.  

■》For eg -> 

If we write a function that adds 2 integers and returns their sum then the return type of this function will be ‘int’ as we will return a sum that is an integer value.

○ When a function does not return any value, in that case the return type of the function is ‘void’.

■》function_name->

○ It is the unique name of that function.  

○ It is always recommended to declare a.                  function before it is used.

■》Parameters->

A function can take some parameters as inputs. These parameters are specified along with their data types.

■ For eg->

if we are writing a function to add 2 integers, the parameters would be passed like –

int add (int num1, int num2)

■》main function ->

The main function is a special function as the computer starts running the code from the beginning of the main function. Main function serves as the entry point for the program.

Example :

public class Main {

   //A METHOD to calculate sum of 2 numbers -

    a & b

   public static void sum(int a, int b) {

       int sum = a + b;

       System.out.println(sum);

   }

   public static void main(String[] args) {

      int a = 10;

      int b = 20;

       sum(a, b); // Function Call

   }

}