Question

Having issues starting an assignment. Still learning so If you don't mind could you explain

public Theater()

Initialize the 2-D array “seats”, with 3 rows and 4 columns. To assign the price
for each seat, you need to open and read from the file “seatPrices.txt”. The file
contains 12 doubles representing the price for each row. All seats in a given
row are the same price, but different rows have different prices. You also need
to initialize “totalSeats” to 0.

public void displayChart()

This method is required to print out the seating chart with costs of the seats
with a tab between columns in the same row and a newline between rows. So
the initial seating chart would be printed:
12.5 12.5 12.5 12.5
10.0 10.0 10.0 10.0
8.0 8.0 8.0 8.0

----

import java.util.Scanner;
import java.io.*;

public class Assignment8
{   public static void main(String[] args)throws IOException
   {
       Theater t = new Theater();
       char command;
       Scanner keyboard = new Scanner(System.in);

      
      
      
       // print the menu
       printMenu();
       do
       {
           // ask a user to choose a command
           System.out.println("\nPlease enter a command or type ?");
           command = keyboard.next().toLowerCase().charAt(0);
           switch (command)
           {
               case 'a': // display remaining seats
                   System.out.println();
                   t.displayChart();
           }/*                   break;
/*               case 'b': // Print total from sales so far
                   System.out.println("\nTotal: " + t.getTotal());
                   break;
               case 'c': // sell ticket

                   if (t.soldOut())
                       System.out.println("\nSorry we are sold out.");
                   else
                   {
                       System.out.print("\nEnter the row you want: ");
                       int row = keyboard.nextInt();
                       System.out.print("Enter the column you want: ");
                       int col = keyboard.nextInt();
                       if (t.sellTicket(row, col))
                           System.out.println("\nEnjoy the show!");
                       else
                           System.out.println("\nThe seat is sold and/or is invalid seat!");
                   }
                   break;
               case 'd': // print number of seats sold
                   System.out.println("\nNumber of seats sold: " + t.numSold());
                   break;

               case '?': // display menu
                   printMenu();
                   break;
               case 'q':   // quit
                   break;
               default:
                   System.out.println("Invalid input!");

           }

*/       } while (command != 'q');

   } //end of the main method

   // this method prints out the menu to a user
   public static void printMenu()
   {
       System.out.print("\nCommand Options\n"
           + "-----------------------------------\n"
           + "a: print seating chart\n"
           + "b: display total sales\n"
           + "c: sell ticket\n"
           + "d: display number of seats sold\n"
           + "?: display the menu again\n"
           + "q: quit this program\n\n");
   } // end of the printMenu method

}
-----

package assignment8;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class Theater
{
//a two dimensional double array to hold the prices of the seats
//double to hold the total amount of sales generated from the theater.
   private double seats[][];
   double totalSales=0;
  
   String fileName="seatPrices.txt";
   String seatPrices="";
  
   static final int NUM_ROWS=3;
   static final int NUM_COLUMNS=4;
  
  
/*Initialize the 2-D array “seats”, with 3 rows and 4 columns
To assign the price for each seat, you need to open and read from the file “seatPrices.txt”. The file
contains 12 doubles representing the price for each row.
All seats in a given row are the same price, but different rows have different prices
*/
   public Theater()
   {
   Double seats[][]= new Double[NUM_ROWS][NUM_COLUMNS];
   int totalSeats=0;
   Double temp[][]=seats;
  
  
   try
{
// Instantiate a FileReader object to open the input file
// Note: "filename" should match the input file you made in Step 4
          
FileReader fr = new FileReader("seatPrices.txt");
//FileReader fr = new FileReader("/autograder/submission/" + fileName);
          
// BufferedReader is for efficient reading of characters
BufferedReader bfReader = new BufferedReader(fr);


// As we have determined the number of lines in our file, we will
// use constants to define the loop conditions

for (int r = 0; r {
for (int c= 0; c < NUM_COLUMNS; c++)
{
// Read a line from the file
// invoke .readLine() on the BufferedReader bfReader
// and save the returned value to the element at array position (i, j)
// -->
    seatPrices= bfReader.readLine();
    temp[r][c]=Double.valueOf(seatPrices);
      
   
   
}
seats=temp;

}
  
bfReader.close();

}
catch (FileNotFoundException e)
{
System.err.println("File not found");
}
catch (IOException e)
{
System.err.println("I/O error occurs");
}
        
   }

   public void displayChart()
   {   
  
   for (int r = 0; r {
for (int c= 0; c < NUM_COLUMNS; c++)
{
   System.out.print(seats[r][c]+ "\t");
}
System.out.println();
   }

   }
}

-------

seatPrices.txt

12.50
12.50
12.50
12.50
10.00
10.00
10.00
10.00
8.00
8.00
8.00
8.00

Answer 1

I have provided a detailed comment in the program for explaining the Theather() constructor, but if you still find it confusing please feel free to comment which part you're not getting I will surely try my best to explain

Program

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

class Theater {
   // a two-dimensional double array to hold the prices of the seats
   // double to hold the total amount of sales generated from the theater.
   private double seats[][];
   double totalSales = 0;

   String fileName = "seatPrices.txt";
   String seatPrices = "";

   static final int NUM_ROWS = 3;
   static final int NUM_COLUMNS = 4;

   /*
   * Initialize the 2-D array “seats”, with 3 rows and 4 columns To assign the
   * price for each seat, you need to open and read from the file
   * “seatPrices.txt”. The file contains 12 doubles representing the price for
   * each row. All seats in a given row are the same price, but different rows
   * have different prices
   */
   public Theater() {

       // initializing the 2d array seats
       // you were creating new seats[][] instead of using global seats[][]
      
       //Double seats[][] = new Double[NUM_ROWS][NUM_COLUMNS]; old code
       seats = new double[NUM_ROWS][NUM_COLUMNS];//modified code

       // i dont know the purpose of his variable
       // as it is not being used anywhere
       // maybe its created for future use
       int totalSeats = 0;

       // there is no need to create a temporary array
       // for putting price in the seats array
       // you can directly use seats array
       /* Double temp[][] = seats; */

       try {

           // Instantiate a FileReader object to open the input file
           // Note: "filename" should match the input file you made in Step 4

           // instantiating fileReader for reading the streams of characters in the file
           FileReader fr = new FileReader("data.txt");// change the name of file accodingly

           // FileReader fr = new FileReader("/autograder/submission/" + fileName);

           // BufferedReader is for efficient reading of characters
           BufferedReader bfReader = new BufferedReader(fr);

           for (int r = 0; r < NUM_ROWS; r++) {// for rows
               seatPrices = bfReader.readLine();// reading the data from the file
               for (int c = 0; c < NUM_COLUMNS; c++) {// for columns
                   // converting the data to double and
                   // then puuting it to the specific array position provied by the loop
                   seats[r][c] = Double.valueOf(seatPrices);

               }
               // seats = temp;

           }

           // closing the bufferedReader for releasing the resources
           bfReader.close();

           // for handling exceptions
       } catch (FileNotFoundException e) {
           System.err.println("File not found");
       } catch (IOException e) {
           System.err.println("I/O error occurs");
       }

   }

   public void displayChart() {
       for (int r = 0; r < NUM_ROWS; r++) {
           for (int c = 0; c < NUM_COLUMNS; c++) {
               System.out.print(seats[r][c] + "\t");
           }
           System.out.println();
       }

   }
}

public class Test {
   public static void main(String[] args) throws IOException {
       Theater t = new Theater();
       char command;
       Scanner keyboard = new Scanner(System.in);

       // print the menu
       printMenu();
       do {
           // ask a user to choose a command
           System.out.println("\nPlease enter a command or type ?");
           command = keyboard.next().toLowerCase().charAt(0);
           switch (command) {
           case 'a': // display remaining seats
               System.out.println();
               t.displayChart();
           }
           /*
           * break; /* case 'b': // Print total from sales so far
           * System.out.println("\nTotal: " + t.getTotal()); break; case 'c': // sell
           * ticket
           *
           * if (t.soldOut()) System.out.println("\nSorry we are sold out."); else {
           * System.out.print("\nEnter the row you want: "); int row = keyboard.nextInt();
           * System.out.print("Enter the column you want: "); int col =
           * keyboard.nextInt(); if (t.sellTicket(row, col))
           * System.out.println("\nEnjoy the show!"); else
           * System.out.println("\nThe seat is sold and/or is invalid seat!"); } break;
           * case 'd': // print number of seats sold
           * System.out.println("\nNumber of seats sold: " + t.numSold()); break;
           *
           * case '?': // display menu printMenu(); break; case 'q': // quit break;
           * default: System.out.println("Invalid input!");
           *
           * }
           *
           */ } while (command != 'q');

   } // end of the main method

   // this method prints out the menu to a user
   public static void printMenu() {
       System.out.print("\nCommand Options\n" + "-----------------------------------\n" + "a: print seating chart\n"
               + "b: display total sales\n" + "c: sell ticket\n" + "d: display number of seats sold\n"
               + "?: display the menu again\n" + "q: quit this program\n\n");
   } // end of the printMenu method

}

Output

Input