Question

Write a program named Intervals.java that will take two time intervals (a starting and ending time) and compare them. The program first prompts the user for an earlier and later interval. Each interval consists of two numbers in 24-hour format (for example, 1507 for 3:07 p.m.):

Enter earlier start and end time as two 24-hour format times: 0700 1045
Enter later start and end time as two 24-hour format times: 0815 1130

You may presume that the user will enter the intervals with the start time and end time in the correct order.

The program will then calculate how many minutes are in each interval, which one is longer, and whether the intervals overlap (does the later interval start before the first one is finished):

The earlier interval is 225 minutes long.
The later interval is 195 minutes long.
The earlier interval is longer.
These intervals overlap.

Here is output from another run of the program:

Enter earlier start and end time as two 24-hour format times: 1340 1445
Enter later start and end time as two 24-hour format times: 1500 1710
The earlier interval is 65 minutes long.
The later interval is 130 minutes long.
The later interval is longer.
These intervals do not overlap.

If the intervals are of equal length, your output should say they are equally long. If the later interval starts at the same time that the earlier interval ends, they do not overlap.

Plan this program before you start writing it! No single part of this program is tremendously difficult, but there are many parts.

Hint: Convert the times to number of minutes after midnight. This will make your calculations much easier. For example, 0507 is 5 hours and 7 minutes past midnight, or 307 minutes past midnight. You will want to use / and % with 100 to split up the time into the hours and minutes part, but use 60 when calculating total minutes!

Extra challenge: Give the correct answer even if the user enters the beginning and end times for an interval in the wrong order, or if they enter the later interval first and the earlier interval second.

Answer 1

Thanks for the question.

Below is the code you will be needing Let me know if you have any doubts or if you need anything to change.

Thank You !!

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import java.util.Scanner;

public class Intervals {


    public static void main(String[] args) {


        String firstStartTime, firstEndTime;
        String secondStartTime, secondEndTime;
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter earlier start and end time as two 24-hour format times: ");
        firstStartTime = scanner.next();
        firstEndTime = scanner.next();

        System.out.print("Enter later start and end time as two 24-hour format times: ");
        secondStartTime = scanner.next();
        secondEndTime = scanner.next();

        int earlierDuration = duration(firstStartTime, firstEndTime);
        int laterDuration = duration(secondStartTime, secondEndTime);


        System.out.println("The earlier interval is " + earlierDuration + " minutes long.");
        System.out.println("The later interval is " + laterDuration + " minutes long.");

        if (earlierDuration > laterDuration) {
            System.out.println("The earlier interval is longer.");
        } else if (earlierDuration < laterDuration) {
            System.out.println("The later interval is longer.");
        }

        if (isOverlapping(firstStartTime, firstEndTime, secondStartTime, secondEndTime)) {
            System.out.println("These interval overlap.");
        } else {
            System.out.println("These interval do not overlap.");
        }

    }

    private static int duration(String start, String end) {

        return absoluteTime(end) - absoluteTime(start);
    }

    private static int absoluteTime(String time) {

        String hours = time.substring(0, 2);
        String minutes = time.substring(2);

        // calcuate time from midnight
        int totalMinutes = Integer.parseInt(hours) * 60 + Integer.parseInt(minutes);
        return totalMinutes;

    }

    private static boolean isOverlapping(String earlierStart, String earlierEnd, String laterStart, String laterEnd) {

        int earlierAbsStart = absoluteTime(earlierStart);
        int earlierAbsEnd = absoluteTime(earlierEnd);
        int laterAbsStart = absoluteTime(laterStart);
        int laterAbsEnd = absoluteTime(laterEnd);

        if (earlierAbsStart < laterAbsStart && laterAbsStart < earlierAbsEnd) return true;
        else if (earlierAbsStart < laterAbsEnd && laterAbsEnd < earlierAbsEnd) return true;

        else if (laterAbsStart < earlierAbsStart && earlierAbsStart < laterAbsEnd) return true;
        else if (laterAbsStart < earlierAbsEnd && earlierAbsEnd < laterAbsEnd) return true;
        else return false;
    }


}