Difference between Function and Method in Java

In this tutorial, we are going to learn about the differences between function and method in Java.

What is Method in Java?

In Java, a method is a block of code that performs a specific task and can be executed by calling its name. It is a fundamental building block of object-oriented programming and helps in organizing and structuring code into reusable components. Methods are declared within classes and can have a return type, parameters, and body. The return type specifies the type of value that the method will return after its execution. If a method does not return any value, its return type is specified as void.

What is Function in Java?

In Java, the term "function" is a block of code that performs a specific task. However, in a strict sense, the term "function" is commonly associated with programming languages that support functional programming paradigms, where functions are treated as first-class citizens and can be passed as arguments, returned as values, and stored in variables.

Example 1

In the above example, we have a class called MethodFunctionDemo that contains three members. The add function is a static method that takes two integer parameters (a and b) and returns their sum. The printWelcomeMessage method is a non-static method that doesn't take any parameters. It simply prints a welcome message to the console. The factorial method is a non-static method that calculates the factorial of a number n using recursion. It returns the factorial value.

FileName: MethodFunctionDemo.java

public class MethodFunctionDemo {
 // Function: Adds two numbers and returns the sum of that two numbers
 public static int add(int a, int b) {
 return a + b;
 }
 // Method: Prints a welcome message
 public void printWelcomeMessage() {
 System.out.println("Welcome to the JavaTpoint!");
 }
 // Method: Computes the factorial of a number recursively
 public int factorial(int n) {
 if (n == 0 || n == 1) {
 return 1;
 } else {
 return n * factorial(n - 1);
 }
 }
 public static void main(String[] args) {
 MethodFunctionDemo demo = new MethodFunctionDemo();
 // Function call
 int sum = add(5, 3);
 System.out.println("Sum: " + sum);
 // Method call
 demo.printWelcomeMessage();
 // Method call
 int factorialResult = demo.factorial(5);
 System.out.println("Factorial: " + factorialResult);
 }
}

Output

Sum: 8
Welcome to the JavaTpoint!
Factorial: 120

Example 2

In the above example, The findMax function is a static method that takes an integer array (arr) as a parameter. It iterates over the elements of the array and finds the maximum element. The maximum value is then returned and the printArray method is a non-static method that takes an integer array (arr) as a parameter. It loops through the elements of the array and prints each element to the console.

FileName: MethodFunctionExample.java

public class MethodFunctionExample {
 // Function: It Finds the maximum element in the array
 public static int findMax(int[] arr) {
 int max = arr[0];
 for (int i = 1; i < arr.length; i++) {
 if (arr[i] > max) {
 max = arr[i];
 }
 }
 return max;
 }
 // Method: Prints all the elements inside the array
 public void printArray(int[] arr) {
 for (int element : arr) {
 System.out.print(element + " ");
 }
 System.out.println();
 }
 public static void main(String[] args) {
 int[] numbers = { 5, 8, 2, 10, 3 };
 // Function call
 int maximum = findMax(numbers);
 System.out.println("Maximum element: " + maximum);
 MethodFunctionExample example = new MethodFunctionExample();
 // Method call
 example.printArray(numbers);
 }
}

Output

Maximum element: 10
5 8 2 10 3