Types of Methods in Java

A Java method is a collection of statements that are grouped together to perform an operation. A method in Java is a block of code that, when called, performs specific actions mentioned in it. For instance, if you have written instructions to draw a circle in the method, it will do that task.

You can insert values or parameters into methods, and they will only be executed when called. They are also referred to as functions. The primary uses of methods in Java are:

It allows code re-usability (define once and use multiple times)
You can break a complex program into smaller chunks of code
It increases code readability

Two Types of Methods :
1. User-defined Methods : We can create our own method based on our requirements.
2. Standard Library Methods : These are built-in methods in Java that are available to use.

Syntax:
   Access_ specifier Return_type Method_name ( Parameter list )
   {
        // body of method ;
   }

Access specifier :

Public : You can access it from any class
Private : You can access it within the class where it is defined
Protected : Accessible only in the same package or other subclasses in another package

Return type :

Int : Int as the return type if the method returns value.
Void : Void as the return type if the method returns no value.

Parameter list :

It is a list of arguments (data_type variable_name) that will be used in the method.

Method body :

This is the set of instructions enclosed within curly brackets.

This is a Java program that demonstrates different types of user-defined methods. Let's go through each method one by one:

add() - This is a no return method without arguments that adds two integer values and displays the result.
sub(int x, int y) - This is a no return method with arguments that subtracts the second integer value from the first integer value and displays the result.
mul() - This is a return method without arguments that multiplies two integer values and returns the result.
div(int x, int y) - This is a return method with arguments that divides the first integer value by the second integer value and returns the result as a float.
factorial(int n) - This is a recursive function that calculates the factorial of a given integer value and returns the result. It uses the formula n! = n * (n-1) * (n-2) * ... * 1. The base case for the recursion is when n equals 1, in which case the function returns 1.

In the main() method, an object of the Methods class is created and the different methods of the class are called to demonstrate their usage.

Overall, this program demonstrates the different types of user-defined methods that can be created in Java and how they can be used in a program.

Source Code

class Methods {
    //No Return W/o args
    public void add() {
        int a = 123;
        int b = 10;
        System.out.println("Addition : " + (a + b));
    }
 
    //No Return With Args
    public void sub(int x, int y) {
        System.out.println("Subtraction : " + (x - y));
    }
    //Return Without Args
    public int mul() {
        int a = 123;
        int b = 10;
        return a * b;
    }
 
    //Return With Args
    public float div(int x, int y) {
        return (x / y);
    }
 
    //Recursion Function
    public  int factorial(int n)//5!  =1*2*3*4*5=120
    {
        if(n==1)
            return 1;
        else
            return (n*factorial(n-1));
    }
    /*
factorial(5)
factorial(4)
factorial(3)
factorial(2)
factorial(1)
 
return 1;
return 2*1;
return 3*2;
return 4*6;
return 5*24;
 
 
* */
 
}
 
 
//Type of User Define Methods in Java
public class functions {
    public static void main(String args[]) {
        Methods o = new Methods();
        o.add();
        o.sub(123, 10);
        System.out.println("Muli : "+o.mul());
        System.out.println("Division : "+o.div(123,10));
    }
}

Output

Addition : 133
Subtraction : 113
Muli : 1230
Division : 12.0

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