Java 8 – How to Get the Number of Days Between Two Dates

Introduction

Java 8 introduced the java.time package, which provides a more robust and flexible API for handling date and time. One common task is calculating the number of days between two dates, which is useful in various applications such as scheduling, logging, or calculating time intervals. The java.time package simplifies this process with classes like LocalDate and Period.

In this guide, we’ll explore how to calculate the number of days between two dates using Java 8’s java.time package.

Table of Contents

• Problem Statement
• Solution Steps
• Java Program
  • Calculate the Number of Days Between Two Dates
• Advanced Considerations
• Conclusion

Problem Statement

The task is to create a Java program that:

• Calculates the number of days between two LocalDate objects.

Example:

• Input: Two LocalDate objects representing 2024-08-01 and 2024-08-28.
• Output: An integer representing the number of days between the two dates, such as 27.

Solution Steps

1. Create LocalDate Objects: Represent the start and end dates.
2. Use ChronoUnit.DAYS.between(): Calculate the number of days between the two LocalDate objects.
3. Handle the Result: The result will be an integer representing the number of days between the dates.

Java Program

Calculate the Number of Days Between Two Dates

The following example demonstrates how to calculate the number of days between two dates in Java 8.

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

/**
 * Java 8 - How to Get the Number of Days Between Two Dates
 * Author: https://www.rameshfadatare.com/
 */
public class DaysBetweenDates {

    public static void main(String[] args) {
        // Step 1: Create LocalDate objects for the start and end dates
        LocalDate startDate = LocalDate.of(2024, 8, 1);
        LocalDate endDate = LocalDate.of(2024, 8, 28);

        // Step 2: Calculate the number of days between the two dates
        long daysBetween = ChronoUnit.DAYS.between(startDate, endDate);

        // Step 3: Display the number of days
        System.out.println("Number of days between " + startDate + " and " + endDate + " is: " + daysBetween);
    }
}

Output

Number of days between 2024-08-01 and 2024-08-28 is: 27

Explanation

• Date Creation: LocalDate.of(2024, 8, 1) and LocalDate.of(2024, 8, 28) create LocalDate instances representing the start and end dates, respectively.
• Days Calculation: ChronoUnit.DAYS.between(startDate, endDate) calculates the number of days between the two dates. This method returns a long value representing the total number of days.
• Display: The result is then printed, showing the number of days between the two specified dates.

Advanced Considerations

• Inclusive vs. Exclusive Dates: The ChronoUnit.DAYS.between() method calculates the number of days between two dates exclusively. This means that the start date is not counted, but the end date is. If you need an inclusive count, you might need to add 1 to the result.

• Negative Values: If the start date is after the end date, the method will return a negative number. Consider validating the dates before performing the calculation.

• Other Temporal Units: You can also calculate the difference in weeks, months, or years by replacing ChronoUnit.DAYS with ChronoUnit.WEEKS, ChronoUnit.MONTHS, or ChronoUnit.YEARS.

Conclusion

This guide covers how to calculate the number of days between two dates using Java 8’s java.time package. The ChronoUnit.DAYS.between() method provides a simple and effective way to calculate date differences, making it easy to determine the number of days between any two LocalDate objects. Whether for scheduling, logging, or calculating time intervals, this approach is essential in modern Java applications.