Question

Write a program that reads a string from the keyboard and tests whether it contains a valid time. Display the time as described below if it is valid, otherwise display a message as described below. The input date should have the format hh:mm:ss (where hh = hour, mm = minutes and ss = seconds in a 24 hour clock, for example 23:47:55).

Here are the input errors (exceptions) that your program should detect and deal with:
Receive the input from the user (give an example of the format you are expecting the user to use when entering the time) and check for the following:
⦁   missing one of parts (the hour or the minutes or the second is missing.
⦁   hh, mm or ss is not numeric
⦁   hh not between 0 and 23
⦁   mm is not between 0 and 59
⦁   ss is not between 0 and 59

Be specific when reporting an error. For example, “The input 24:04:20 contains an invalid hour of 24”.

If the user gives you invalid input, start the whole process again by asking the user for a valid time. Keep prompting the user until you get a valid time. A while (!valid) loop would work well here.

If the time is valid, then output a message in this format, “23:45:16 is 11:45:16 pm”. That is, convert it to the am/pm format.

The program should be coded as a series of method calls (within the try block, inside the while loop):
⦁   getInput( ) – asks the user for the time. Uses the String split( ) method to break it into 3 parts. Checks that there are 3 parts and throws a MissingColonException if there aren’t. The method returns the String array.
⦁   checkHour( ) – receives the hour String part of the array, tries to convert it to a numeric value, then checks if the number is between 0 and 23. Throws NumberFormatException and HourException
⦁   checkMinutes( ) – similar to checkHour( )
⦁   checkSeconds( ) – similar to checkHour( )

Notes:
⦁   Be sure that the output that you submit shows that your program has tested ALL the different types of errors that can occur.

⦁   The messages output by the catch blocks should be very specific. For example, output “24 is an invalid hour”, or “23:15 is missing one part”, rather than simply “invalid hour” or “invalid input”. The first 2 messages allow the user to better understand what input caused the problem; the other messages leave the user guessing about what the source of the problem is.

⦁   You do not need to write code for the NumberFormatException class; this already exists as part of Java.

⦁   You’ll need to write class definition files for the other exceptions described above.

⦁   Because Dr. Java does not show what the input is, you should write out the input before you do anything else (so that your professor can see what you entered).

Answer 1

Here are the 3 classes

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public class HourException extends Throwable {
}

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public class MissingColonException extends Exception {

}

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import java.util.Scanner;

public class TimeValidator {

    private static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {

        while (true) {
            String militaryTime = "";
            try {
                militaryTime = getInput();
                String[] parts = militaryTime.split(":");

                boolean hourValid = false;
                try {
                    hourValid = checkHour(parts[0]);
                } catch (NumberFormatException nfe) {
                    System.out.println("The input " + militaryTime + " contains an invalid hour of " + parts[0]);
                } catch (HourException e) {
                    System.out.println("The input " + militaryTime + " contains an invalid hour of " + parts[0]);
                }
                boolean minuteValid = false;
                try {
                    minuteValid = checkMinutes(parts[1]);
                } catch (NumberFormatException nfe) {
                    System.out.println("The input " + militaryTime + " contains an invalid minutes of " + parts[1]);
                }
                boolean secondValid = false;
                try {
                    secondValid = checkSeconds(parts[2]);
                } catch (NumberFormatException nfe) {
                    System.out.println("The input " + militaryTime + " contains an invalid seconds of " + parts[2]);
                }

                if (hourValid && minuteValid && secondValid) {
                    String standardTime = convertToStandardTime(parts[0], parts[1], parts[2]);
                    System.out.println(standardTime);
                    break;
                } else {
                    continue;
                }

            } catch (MissingColonException e) {
                System.out.println("Time is not is correct format, colon missing");
            }

        }
    }

    private static String convertToStandardTime(String hours, String minutes, String seconds) {

        int hour = Integer.parseInt(hours);
        int minute = Integer.parseInt(minutes);
        int second = Integer.parseInt(seconds);
        String amPm = "am";
        StringBuilder buildTime = new StringBuilder();
        if (hour > 12) {
            amPm = "pm";
            buildTime.append((hour - 12)).append(":");
        } else if (hour < 10) {
            buildTime.append("0").append((hour)).append(":");
        } else {
            buildTime.append((hour)).append(":");
        }
        if (minute < 10) {
            buildTime.append("0").append(minute).append(":");
        } else {
            buildTime.append(minute).append(":");
        }
        if (second < 10) {
            buildTime.append("0").append(second);
        } else {
            buildTime.append(second);
        }

        buildTime.append(" ").append(amPm);
        return buildTime.toString();

    }

    private static boolean checkHour(String hours) throws HourException {


        int hour = Integer.parseInt(hours);
        if (0 <= hour && hour < 24) {
            return true;

        }else{
            throw new HourException();
        }


    }

    private static boolean checkMinutes(String mins) {

        int minutes = Integer.parseInt(mins);
        if (0 <= minutes && minutes < 59) {
            return true;
        }

        return false;
    }

    private static boolean checkSeconds(String secs) {

        int seconds = Integer.parseInt(secs);
        if (0 <= seconds && seconds < 59) {
            return true;
        }

        return false;
    }

    private static String getInput() throws MissingColonException {
        System.out.println("input date should have the format hh:mm:ss " +
                "(where hh = hour, mm = minutes and ss = seconds in a 24 hour clock, " +
                "for example 23:47:55): ");

        String militaryTime = sc.nextLine();
        if (militaryTime.contains(":")) {
            String[] timeParts = militaryTime.split(":");
            if (timeParts.length == 3) {
                return militaryTime;
            } else {
                throw new MissingColonException();
            }
        }
        throw new MissingColonException();
    }


}

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