A small airline has just purchased a computer for its new automated reservations system. You have been asked to develop the new system. You are 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 is 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 elements 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 is 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."

Here is the simple JAVA program.

import java.util.Scanner;   // to take input from user

public class AirlineReservationSystem {  //airline reservation class

 public static void main(String[] args) {  //start of main() function body

Scanner input=new Scanner(System.in);   //Scanner class instance

int first_class=0;  //stores the first class seat numbers

int eco_class=5; //holds the economy class seat numbers

int quit;  //used to quit the reservation system  

System.out.println("Welcome to the AIRLINE RESERVATION SYSTEM!");  // displays welcome message

do{   //start of do while loop  

//displays following messages for user to make choice between 2 sections

System.out.println("Please type 1 for First Class ");

System.out.println("Please type 2 for Economy ");

int choice=input.nextInt();  //takes the choice from user

switch(choice){ // takes choice of user from first class or economy section

 case 1:  //when user enters first class as choice

   first_class++;  

//increments count of first class by 1 every time user reserves a seat in first //class

if (first_class<=5){  // the seats in first class section should be between 1-5

//displays message of seat reserved in first class

  System.out.println("Your seat is assigned in First Class.");    

System.out.println("Your seat number is "+first_class);  

//assigns seat number in first class    }      

   else{

// displays following message when number of seats in first class exceed 5

System.out.println("No seat is available in First Class");

//asks user if he wants to placed in economy class when there is no seat //available in first class

System.out.println("Do you want to be placed at the Economy section?(1.yes\t2.no)");

 int full=input.nextInt();  //reads yes or no (1 or 2) from user

   if (full==1){  //if user entered 1

 System.out.println("Enter 1 to return to main menu to reserve a seat in Economy class.");

   }  // asks user to press 1 to go to main menu

   else{  //displays following message if user enters 2

 System.out.println("Next flight leaves in 3 hours.");}  }

   break;

case 2:  //when the user choose to reserve seat in economy class

                        eco_class++;  

//increments count of first class by 1 every time user reserves a seat in //economy class

//the seats of economy class ranges from 6 to 10  

if ((eco_class>5)&&(eco_class<=10)){  

//display message about economy class seat reservation

System.out.println("Your seat is assigned in Economy Class.");

//assigns seat number in economy class    

 System.out.println("Your seat number is "+eco_class);  }  

   else{

// displays following message when number of seats in economy class //exceed 10

System.out.println("No seat is available in Economy Class");

//asks user if he wants to placed in first class when there is no seat //available in economy class

System.out.println("Do you want to be placed at the First class section?(1.yes\t2.no)");  

 int full=input.nextInt(); //reads yes or no (1 or 2) from user

   if (full==1){ //if user entered 1

 System.out.println("Enter 1 to return to main menu to reserve a seat in business class.");  

// asks user to press 1 to go to main menu }

   else{  //displays following message if user enters 2

 System.out.println("Next flight leaves in 3 hours."); }} }

System.out.println("1.main menu\t2.quit");  

quit=input.nextInt();

//if user presses 2 it reads that value from user and store it in quit variable

 }while (quit==1);  //the loop stops when user chooses quit

 System.out.println("Bye! Have a nice day!"); }  }  

//displays message when user quits the reservation system

Explanation:

The program is well explained in the comments mentioned with each line of the program. The program uses switch statement for the user to make choice between first and economy class. If the user selects first class, then his seat is reserved in first class and a seat number is generated to user. The range of first class seats is from 1 to 5. When this range is exceeded the  person is asked if he wants to be placed in economy class. If the user presses one then the person is asked to go back to main menu and reserve seat in economy class. If user enters 2 then the system exits. Same flow goes with the economy class seat reservation. The do while loop keeps executing until the user quits the system. If the user presses 2 to quit, the system exits after displaying bye message.