Nested if in Java programming

It is perfectly all right if we write an entire if-else construct within either the body of the if statement or the body of an else statement.

Syntax :

if( boolean_expression 1) {
   /* Executes when the boolean expression 1 is true */
   if(boolean_expression 2) {
      /* Executes when the boolean expression 2 is true */
   }
}               
                                    

Example:

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        Scanner sc; // Declare a Scanner object
        sc = new Scanner(System.in); // Initialize the Scanner object to read input from the console
        int x; // Declare an integer variable 'x'

        System.out.print("Enter any number: "); // Prompt the user to enter a number
        x = sc.nextInt(); // Read an integer input from the user and store it in 'x'

        // Check if the entered number is greater than 0
        if (x > 0) {
            // If true, check if the number is even or odd
            if (x % 2 == 0) {
                System.out.print("X is EVEN"); // If even, print "X is EVEN"
            } else {
                System.out.print("X is ODD"); // If odd, print "X is ODD"
            }
        } else {
            // If false (i.e., the number is not greater than 0), print "Not a Natural Number"
            System.out.print("Not a Natural Number");
        }
    } // main method closed
} // class closed

Enter any number: 12
X is EVEN
                                

Enter any number: 3
X is ODD
                                

Enter any number: -12
Not a Natural Number