Before we see the program, lets see how to determine whether a year is a leap year mathematically:
To determine whether a year is a leap year, follow these steps:
1. If the year is evenly divisible by 4, go to step 2. Otherwise, go to step 5.
2. If the year is evenly divisible by 100, go to step 3. Otherwise, go to step 4.
3. If the year is evenly divisible by 400, go to step 4. Otherwise, go to step 5.
4. The year is a leap year (it has 366 days).
5. The year is not a leap year (it has 365 days)

Using Java

import java.util.Scanner;
public class Demo {

    public static void main(String[] args) {

    	int year;
    	Scanner scan = new Scanner(System.in);
    	System.out.println("Enter any Year:");
    	year = scan.nextInt();
    	scan.close();
        boolean isLeap = false;

        if(year % 4 == 0)
        {
            if( year % 100 == 0)
            {
                if ( year % 400 == 0)
                    isLeap = true;
                else
                    isLeap = false;
            }
            else
                isLeap = true;
        }
        else {
            isLeap = false;
        }

        if(isLeap==true)
            System.out.println(year + " is a Leap Year.");
        else
            System.out.println(year + " is not a Leap Year.");
    }
}
Output:

Enter any Year: 
2001
2001 is not a Leap Year.