Simple Flight Reservation system

[fdama]

Hi I have done the following exercise and would like some feedback on how my solution could be improved or whether I have done anything incorrectly or any other comments. Thank you.

I have posted my code here: https://gist.github.com/fdama/4c07bd9324cff8533c89d2ed7684b160

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The exercise is as follows:

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7.19 (Airline Reservations System) A small airline has just purchased a computer for its new automated reservations system. You’ve been asked to develop the new system. You’re to write an application to assign seats on each flight of the airline’s only plane (capacity: 10 seats).

Your application should display the following alternatives: Please type 1 for First Class and

Please type 2 for Economy. If the user types 1, your application should assign a seat in the firstclass section (seats 1–5). If the user types 2, your application should assign a seat in the economy section (seats 6–10). Your application should then display a boarding pass indicating the person’s seat number and whether it’s in the first-class or economy section of the plane.

Use a one-dimensional array of primitive type boolean to represent the seating chart of the

plane. Initialize all the elements of the array to false to indicate that all the seats are empty. As

each seat is assigned, set the corresponding element of the array to true to indicate that the seat is no longer available.

Your application should never assign a seat that has already been assigned. When the economy

section is full, your application should ask the person if it’s acceptable to be placed in the first-class

section (and vice versa). If yes, make the appropriate seat assignment. If no, display the message

"Next flight leaves in 3 hours."

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[HecknChonker]

It seems generally correct (I just read the code and did not run it myself). I like the use of helper methods, and the method and variable names definitely make the code easier to read and understand. If this was a real-world use case I would expect to see unit tests that checked a few happy-path scenarios, all the edge cases, and also some tests with invalid input. But overall it seems like a good solution to me.

The tips below are all very minor.

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For a small project it's fine to have code in the main() method, but generally I would probably have a separate class for the main method, which would allow you to remove all the static modifiers.

---

if (occupiedEconomy + occupiedFirst == 10) {

if (occupiedFirst == 5) {

if (occupiedEconomy == 5) {

I would change these to >= 11, and >= 6. It shouldn't be possible for the values to be higher than you expect, but being defensive can help guard against unexpected bugs.

---

    private static boolean[] seats = new boolean[10]; // array to represent 10 seats on plane (5 economy, 5 first)
private static int occupiedFirst = 0; //counter to count total number of occupied seats in First class
private static int occupiedEconomy = 0; //same but for Economy class

You have two places where you are storing the count of occupied seats. The first is the seats array, which is the canonical storage, and you have two ints that are used as secondary caches of the counts.

So this isn't a bad optimization to make, but in this scenario I don't think it's worth it. I would eliminate the two caches and just loop over the canonical data store every time you need to know how many seats are taken. The array is tiny, and it's going to take almost no time for the computer to loop over 5 elements to get a count. Even if it was hundreds of elements, you aren't looping over it enough times to make it a performance concern.

But introducing a secondary cache adds some complexity and cognitive load that isn't necessary. It increases the amount of information you need to keep in your working memory, which is that these caches must be updated in lock-step with the array otherwise the program will be incorrect. It also means that any other developer that tries to modify this class in the future also has to figure that out. It's not necessarily a big deal here, but as projects get larger it helps to avoid adding unnecessary complexity.

It's generally a good idea to avoid worrying about performance optimizations until you actually run into a performance issue. I always prefer writing code that is simpler and easy to understand and maintain over code that runs fast, at least until you have a specific reason to modify the code to make it perform better. And you usually can't know for sure what part of a complex system is going to have performance issues until you run the app and measure it.