How can I update the data inside of an array to be false instead of true?

Question

This program is to reserve time available from three different games. So far in the program, I had printed the two different menus on that shows the game and the other one shows the available time Slots. the Program is set to be an infinite loop so other users have the chance to pick a game and reserve time as well. This is where my problem comes, the second time the program runs it stills displays the time that was previously picked.

import java.util.Scanner;

public class GameReservationSystem {

    public static Scanner input = new Scanner(System.in);
    static String[] timeSlots = {"1-2pm", "2-3pm", "3-4pm", "4-5pm"};
    static String[] Games = {"Backganmon", "Chess", "Dominoes"};
    static boolean avaliableTime[][] = new boolean[Games.length][timeSlots.length];
    static int userChoice;

    public static void main(String[] args) {
        for (int i = 0; i < Games.length; i++) {
            for (int j = 0; j < timeSlots.length; j++) {
                avaliableTime[i][j] = true;
            }
        }

        mainMenu();

    }

    public static void mainMenu() {

        while (true) {
            characterPrint('-');
            for (int i = 0; i < Games.length; i++) {
                System.out.print(i + ". ");
                System.out.println(Games[i]);
            }
            characterPrint('-');
            System.out.println("input a number to choose your game!");
            userChoice = input.nextInt();

            reserveMenu(userChoice);
        }

    }

    public static void reserveMenu(int userChoice) {
        int reserveTime = 0;
        if (userChoice >= 0 && userChoice < Games.length) {

            characterPrint('-');
            System.out.println("This are the avaliable times to play" + Games[userChoice]); 
            for (int i = 0; i < timeSlots.length; i++) {
                System.out.print(i + ". ");
                System.out.println(timeSlots[i]);
            }
            characterPrint('-');
            System.out.println("Input a number to reserve a time: ");
            reserveTime = input.nextInt();

        }
        if (reserveTime >= 0 && reserveTime < timeSlots.length) {

            avaliableTime[userChoice][reserveTime] = false;
            System.out.println("You have succesfully reserve a time to play " + Games[userChoice] + " at" + timeSlots[reserveTime]);
        }

    }

    public static void characterPrint(char c) {
        for (int i = 0; i < 30; i++) {
            System.out.print(c);
        }
        System.out.println();
    }
}

Answer 1

In fact, your problem isn't that you didn't change the boolean values in your table from true to false. Instead, your problem is that you didn't use information in the table before you make reservations. What you were doing is to always set that value to false and print "succesfully reserve", without checking whether that time has already been reserved by someone else.

Try the following code. I also add some codes to handle invalid input number. By the way, "avaliableTime" looks like a typo, so I changed it to "availableTime".

import java.util.Scanner;

public class GameReservationSystem {
    public static Scanner input = new Scanner(System.in);
    static String[] timeSlots = {"1-2pm", "2-3pm", "3-4pm", "4-5pm"};
    static String[] Games = {"Backganmon", "Chess", "Dominoes"};
    static boolean availableTime[][] = new boolean[Games.length][timeSlots.length];
    static int userChoice;

    public static void main(String[] args) {
        for (int i = 0; i < Games.length; i++) {
            for (int j = 0; j < timeSlots.length; j++) {
                availableTime[i][j] = true;
            }
        }

        mainMenu();

    }

    public static void mainMenu() {

        while (true) {
            characterPrint('-');
            for (int i = 0; i < Games.length; i++) {
                System.out.print(i + ". ");
                System.out.println(Games[i]);
            }
            characterPrint('-');
            System.out.println("input a number to choose your game!");
            userChoice = input.nextInt();

            reserveMenu(userChoice);
        }

    }

    public static void reserveMenu(int userChoice) {
        int reserveTime = 0;
        if (userChoice >= 0 && userChoice < Games.length) {

            characterPrint('-');
            System.out.println("This are the avaliable times to play" + Games[userChoice]); 
            for (int i = 0; i < timeSlots.length; i++) {
                if (availableTime[userChoice][i]) {
                    //if false, this time is not available and should not be displayed.
                    System.out.print(i + ". ");
                    System.out.println(timeSlots[i]);
                }
            }
            characterPrint('-');
            System.out.println("Input a number to reserve a time: ");
            reserveTime = input.nextInt();

        }else {
            //handle unexpected game number.
            System.out.println("Invalid game number, please try again."); 
        }

        if (reserveTime >= 0 && reserveTime < timeSlots.length) {
            //what if someone typed 0 although 0 wasn't displayed? (0 wasn't displayed, for example, because it has been reserved by someone else.)
            //So you should check whether it is available by the following line.
            if (availableTime[userChoice][reserveTime]) {
                //if true, this time hasn't been reserved, so it is a valid input.
                availableTime[userChoice][reserveTime] = false;
                System.out.println("You have succesfully reserve a time to play " + Games[userChoice] + " at" + timeSlots[reserveTime]);
            }else {
                //if already false, this time has already been reserved by someone else,
                //thus it is an invalid input.
                System.out.println("This time has already been reserved, please try again.");
            }
        }else {
            System.out.println("Invalid time number, please try again."); 
        }

    }

    public static void characterPrint(char c) {
        for (int i = 0; i < 30; i++) {
            System.out.print(c);
        }
        System.out.println();
    }
}