Question

In Java with Indentations Please!!!!

4.16 LAB: Parsing dates

Complete main() to read dates from input, one date per line. Each date's format must be as follows: March 1, 1990. Any date not following that format is incorrect and should be ignored. Use the substring() method to parse the string and extract the date. The input ends with -1 on a line alone. Output each correct date as: 3/1/1990.

Ex: If the input is:

March 1, 1990
April 2 1995
7/15/20
December 13, 2003
-1

then the output is:

3/1/1990
12/13/2003

Answer 1

Below is your code:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Scanner;

public class ParsingDates {
        public static void main(String[] args) throws ParseException {
                List<String> validDates = new ArrayList<>();
                Scanner sc = new Scanner(System.in);
                String input = "";
                // list to check if month is valid
                List<String> validMonths = Arrays.asList("January", "February",
                                "March", "April", "May", "June", "July", "August", "September",
                                "October", "November", "December");
                // loop till -1 is entered
                while (!input.equals("-1")) {
                        // getting complete date
                        input = sc.nextLine();
                        // check if -1 is entered or not
                        if (!input.equals("-1")) {
                                // check if date contains spaces
                                if (input.indexOf(' ') != -1) {
                                        // getting the month name
                                        String monthName = input.substring(0, input.indexOf(' '));
                                        // validating if month entered is correct and valid
                                        if (validMonths.contains(monthName)) {
                                                // splitting date to day, month and year
                                                String words[] = input.split(" ");
                                                // checking if date contains all three day, month and
                                                // year
                                                if (words.length == 3) {
                                                        // checking if year is valid and is of 4 letters
                                                        if (words[2].length() == 4) {
                                                                // checking if comma is there after day
                                                                if (words[1].indexOf(',') != -1) {
                                                                        String day = words[1].substring(0,
                                                                                        words[1].indexOf(','));
                                                                        // checking if day is valid
                                                                        if (Integer.parseInt(day) <= 31) {
                                                                                // parsing the month number and year
                                                                                String year = words[2];
                                                                                Date date = new SimpleDateFormat("MMMM")
                                                                                                .parse(monthName);
                                                                                Calendar cal = Calendar.getInstance();
                                                                                cal.setTime(date);
                                                                                String monthNum = (cal
                                                                                                .get(Calendar.MONTH) + 1) + "";
                                                                                // adding the valid date in the list
                                                                                validDates.add(monthNum + "/" + day
                                                                                                + "/" + year);
                                                                        }
                                                                }

                                                        }
                                                }
                                        }
                                }
                        }
                }
                sc.close();
                // printing result
                for (String date : validDates) {
                        System.out.println(date);
                }
        }
}

Output

3/1/1990
12/13/2003