Retrieve end date of the month of a given date in Java

You can use the getActualMaximum method in Calendar to retrieve the maximum day of a month.

import java.util.Calendar;
import java.util.Scanner;

public class EndDateOfMonth {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a date (YYYY-MM-DD): ");
        String inputDate = scanner.nextLine();
        String[] parts = inputDate.split("-");
        int year = Integer.parseInt(parts[0]);
        int month = Integer.parseInt(parts[1]) - 1; // Calendar month is 0-based
        int day = Integer.parseInt(parts[2]);
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.YEAR, year);
        calendar.set(Calendar.MONTH, month);
        calendar.set(Calendar.DAY_OF_MONTH, day);
        int endDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        System.out.println("End date of the month: " + endDay);
    }
}

This program reads an input date in the format YYYY-MM-DD from the user, splits it into its constituent parts, and sets the year, month, and day of the Calendar object accordingly. It then uses the getActualMaximum method to retrieve the maximum day of the month, which represents the end date of the month, and prints it to the console.

Note that this program assumes that the user inputs a valid date in the format YYYY-MM-DD. You may want to add error checking to handle invalid input.

References

1. https://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html