Difference Between Function and Method in Java

Function: Within a programme, a function can be called to carry out a specific task. It is a self-contained block of code. It takes input parameters (if any) and can return a value or perform actions.

Method: The Method's operation is similar to that of a function in that it may accept input parameters or arguments and can also return data by having a return type. However, it differs from a function in two key ways.

A method is connected or related to the object instance it is called using.
The Method can only operate upon data present in the class in which it is placed.
It's a key concept in object-oriented programming.

Difference Between Function and Method

Functions	Methods
Do not have reference variables.	Are called by reference variable.
It does not have access control, i.e., it can be declared and defined anywhere in the code.	It contains access control, therefore only within the class should it be declared and defined.
Both object-oriented and non-object-oriented languages are compatible with the Function.	Only object-oriented programming languages can use methods.
It is called individually and by its name.	It is called using the name or reference of its object.
As it is called individually, the data is passed externally or explicitly.	As it is called dependently, the data is passed internally or implicitly.

Implementation of Function in Procedural Programming Language(C):

#include <stdio.h>
//Function to calculate the sum of two integers
int add(int num1, int num2) {
    return num1 + num2;
}

// Main Function
int main() {
    int a = 5, b = 10, sum;
    
    // Calling the add() Function and storing the result in the sum variable
    sum = add(a, b);
    
    printf("The sum of %d and %d is %d", a, b, sum);
    return 0;
}

Output:

The sum of 5 and 10 is 15

Implementation of Function in Object-Oriented Programming Language(JAVA):

Filename: Calculator.java

public class Calculator {
    //Method to calculate the sum of two integers
    public int add(int num1, int num2) {
        return num1 + num2;
    }
    
    // Main Method
    public static void main(String[] args) {
        int a = 5, b = 10, sum;
        Calculator calculator = new Calculator();
        
        // Calling the add() method and storing the result in sum variable
        sum = calculator.add(a, b);
        
        System.out.println("The sum of " + a + " and " + b + " is " + sum);
    }
}

Output: