Get First Day of the Month in Java 8

1. Introduction

Determining the first day of the month is a common requirement in applications related to calendaring, scheduling, or any processing that revolves around monthly cycles. Java's java.time.LocalDate class provides a straightforward way to achieve this.

Key Points

1. LocalDate represents a date without time and timezone.

2. The method withDayOfMonth(1) is used to adjust any date to the first day of its month.

3. This functionality is useful for generating reports, billing cycles, or resetting monthly data.

2. Program Steps

1. Import the LocalDate class.

2. Retrieve the current date.

3. Adjust the date to the first day of the current month.

3. Code Program

import java.time.LocalDate;

public class FirstDayOfMonth {

    public static void main(String[] args) {
        // Step 2: Retrieve the current date
        LocalDate today = LocalDate.now();

        // Step 3: Adjust the date to the first day of the month
        LocalDate firstDayOfMonth = today.withDayOfMonth(1);

        // Print the result
        System.out.println("First day of the current month: " + firstDayOfMonth);
    }
}

Output:

First day of the current month: 2023-10-01  // Output will vary based on the current date

Explanation:

1. LocalDate.now() is called to get the current date according to the system clock in the default time zone.

2. today.withDayOfMonth(1) adjusts the LocalDate object to represent the first day of the current month. This method changes the day of the month while keeping the year and month the same.

3. The result, firstDayOfMonth, shows the first day of the current month. This is particularly useful for applications that need to perform actions aligned with the start of each month, such as resetting counters or initializing new records.