Add Days to a Date

/*
 * Problem : Add days to a date.
 * Input   : A date and a number.
 * Output  : The new date.
 * Approach: Use date arithmetic.
 * Time    : O(1)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String solve(String s) {
        // Step 1: Split the line into the date text and the number of days.
        String[] parts = s.trim().split(" ");

        // Step 2: plusDays moves the date forward (or backward for a negative number). It knows the month lengths and leap years.
        java.time.LocalDate date = java.time.LocalDate.parse(parts[0]).plusDays(Long.parseLong(parts[1]));

        // Step 3: toString gives the ISO form YYYY-MM-DD.
        return date.toString();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.hasNextLine() ? scanner.nextLine() : "";
        System.out.println(solve(s));
    }
}