Leap Year or Not Example in Java

Introduction

Leap Year Or Not is a classic Java console program that demonstrates the concept with complete source code and sample output. Calculation programs apply formulas to solve geometry, statistics and numeric problems.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

A leap year (also known as an intercalary year or a bissextile year) is a year containing one additional day (or, in the case of lunisolar calendars, a month) in order to keep the calendar year synchronized with the astronomical or seasonal year.[1] Because seasons and astronomical events do not repeat in a whole number of days, calendars that have the same number of days in each year, over time, drift with respect to the event that the year is supposed to track.

Leap Year Or Not Example Program

import java.util.Scanner;
public class LeapYearOrNot {
    public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		System.out.print("Enter the year in the format yyyy.\nYEAR= ");
		int year=in.nextInt();
        if (year % 4 == 0) {
            System.out.println(year + " is a leap year");
        } 
		else {
            System.out.println(year + " is not a leap year");
        }
    }
}

Sample Output

Enter the year in the format yyyy.
YEAR= 1944
1944 is a leap year

When to use

Use these formulas in homework tools, engineering calculators or anywhere repeated numeric computation is needed.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. import java.util.Scanner; imports a class used later in the program.

3. A Scanner reads typed input from the keyboard (System.in).

4. A println / print call writes text to the console — part of the sample output below.

5. int year=in.nextInt(); updates a variable used in the calculation or output.

6. The if statement runs the nested code only when the condition is true.

7. A println / print call writes text to the console — part of the sample output below.

8. A println / print call writes text to the console — part of the sample output below.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.