Simple Odd or Even Coding Example

OddOrEven.java

/*

Simple Odd or Even Coding Example

Author: Jon Bonso 
Demo Link: https://www.online-java.com/BYJCIjwhpg

Mathematical Theory:
   - Parity is the property of an integer which determines if it is even or odd.
   - An even number is an integer that can be divided exactly by 2 is an even number.
   - An odd number is an integer that cannot be divided exactly by 2 and has a remainder 
   
Examples of an even number (no remainder after dividing by 2): 

  -2 / 2 = -1
   0 / 2 =  0
   4 / 2 =  2 
   
Examples of an odd number (has a remainder after dividing by 2): 

   3 / 2 =  1.5   (this is also read as 1 Remainder 1 if a modulo operation (%) was used instead of (/) )
   5 / 2 =  2.5   (also considered as 2 Remainder 1)
   7 / 2 =  3.5.  (also considered as 3 Remainder 1)
   
 As you can see above, an odd number is an integer that doesn't produce a 
 remainder (or a decimal) after being divided by the number 2
   
 Notes:

  - The modulo operation (%) can be used to get the remainder of a division, if any.
 
*/

public class OddOrEven
{
    /**
     *  Returns true if the input is an even number or
     *  false if the number is an odd number.
     * 
     *  This function uses a modulo operation to get the
     *  remainder of the division, after the input is divided by 2.
     * 
     */
    static boolean isEven(int i){
        return (i % 2) == 0;    
    }
    
    public static void main(String[] args) {
        System.out.println("Is the number -2 even? " + isEven(-2));
        System.out.println("Is the number -1 even? " + isEven(-1));
        System.out.println("Is the number 0 even? " + isEven(0));
        System.out.println("Is the number 1 even? " + isEven(1));
        System.out.println("Is the number 2 even? " + isEven(2));
        System.out.println("Is the number 3 even? " + isEven(3));
        System.out.println("Is the number 4 even? " + isEven(4));
        
    }
    
}

Odd Or Even Java Demo: https://www.online-java.com/BYJCIjwhpg

Alternative solution via bit masking:

   static boolean isEven(int i){
         return (i & 1) == 0;
    }