Thursday, 9 February 2017

Departmental Store Program in java

import java.util.Scanner;
import java.util.InputMismatchException;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;


public class GroceryListProgram {
   public static void main(String[] commandlineArguments) {
    // Error Checking For 2 Command Line Arguments..
    if (commandlineArguments.length != 2) {
      System.out.println("Please enter the INPUT file name as "
          + "the 1st commandline argument.");
      System.out.println("Please enter the OUTPUT file name as "
          + "the 2nd commandline argument.");
      System.out.println("Please enter exactly "
          + "two (2) commandline arguments.");
    }// end of if
     // if no commandline argument errors, continue program
    else {
      // Declare and instantiate array of 100 Strings
      final Integer MAX_SIZE = new Integer(100);
      String groceryList[] = new String[MAX_SIZE];
      // Set size of grocery list to zero (0) items
      Integer size = new Integer(0);
      // read grocery items from file & store in array for grocery list
      try {
        size = GroceryListProgram.readFromFile(commandlineArguments[0],
            groceryList, size);
      } catch (ArrayIndexOutOfBoundsException exception) {
        System.out.print("ERROR: Too many items in input file. ");
        System.out.println("Please limit to " + MAX_SIZE + " items.");
        // Immediately terminates program
        System.exit(1);
      }

      // user's choice for Menu
      Integer choice = new Integer(0);
      // choice for ending program
      final Integer QUIT = new Integer(4);
      // if the user does not want to QUIT, keep looping
      while (!choice.equals(QUIT)) {
        // get the user's choice
        choice = GroceryListProgram.displayMenu();
        // add grocery item
        if (choice.equals(1)) {
          size = GroceryListProgram.add(groceryList, size);
        }
        // delete grocery item
        else if (choice.equals(2)) {
          size = GroceryListProgram.delete(groceryList, size);
        }
        // display grocery item
        else if (choice.equals(3)) {
          GroceryListProgram.display(groceryList, size);
        }
        // error message
        else if (!choice.equals(QUIT)) {
          System.out.println("ERROR: Please enter an integer in the range from 1 to 4");
        }
      }// end of "while"
       // write to from grocery list array to OUTPUT file
      GroceryListProgram.writeToFile(commandlineArguments[1], groceryList,
          size);
    }// end of "else"
  }// end of main() method


  public static Integer displayMenu() {
    // display menu
    System.out.println();
    System.out.println("\tGROCERY LIST MENU");
    System.out.println("\t Enter 1 to Add");
    System.out.println("\t Enter 2 to Delete");
    System.out.println("\t Enter 3 to Display");
    System.out.println("\t Enter 4 to Quit");
    System.out.print("\tEnter your choice: ");
    // get input from user
    Scanner keyboardInput = new Scanner(System.in);
    Integer choiceOfUser = new Integer(0);
    try {
      // non-integer input will throw InputMismatchException
      choiceOfUser = keyboardInput.nextInt();
    } catch (InputMismatchException exception) {
      // Already have error message in main() method,
      // as choiceOfUser = 0
    }
    System.out.println();
    return choiceOfUser;
  }


  public static Integer readFromFile(String inputFile, String[] array,
      Integer size) throws ArrayIndexOutOfBoundsException {
    // connect to file (does NOT create new file)
    File file = new File(inputFile);
    Scanner scanFile = null;
    try {
      scanFile = new Scanner(file);
    } catch (FileNotFoundException exception) {
      // Print error message.
      // In order to print double quotes("),
      // the escape sequence for double quotes (\") must be used.
      System.out.print("ERROR: File not found for \"");
      System.out.println(inputFile + "\"");
    }
    // if made connection to file, read from file
    if (scanFile != null) {
      // keeps looping if file has more lines..
      while (scanFile.hasNextLine()) {
        // get a line of text..
        String line = scanFile.nextLine();
        // display a line of text to screen..
        // System.out.println(line);
        // array[0] stores the first row (headings) to table
        array[size] = line;
        // increment size
        ++size;
      }
      // In order to print double quotes("),
      // the escape sequence for double quotes (\") must be used.
      System.out.println("Read from file \"" + inputFile + "\"");
    }// end of "if" for connecting to file
    return size;
  }

 
  public static Integer add(String[] list, Integer listSize) {
    // get item from user
    Scanner keyboard = new Scanner(System.in);
    System.out.print("Enter name of item: ");
    String name = keyboard.nextLine();
    System.out.print("Enter number of items: ");
    String number = keyboard.nextLine();
    // add to the end of the array
    list[listSize] = name + ", " + number;
    // add one to the size (one item to end of list)
    return listSize + 1;
  }


  public static Integer delete(String[] list, Integer listSize) {
    // get user input
    System.out.print("Enter the row number of the item you wish to delete: ");
    Scanner keyboard = new Scanner(System.in);
    try {
      // throws an exception if not an integer
      Integer row = keyboard.nextInt();
      // check for negative integers
      if (row <= 0) {
        System.out.println("ERROR: The integer cannot be negative or zero.");
      }
      // check for integer too big
      else if (row > listSize - 1) {
        System.out.println("ERROR: The integer is too big for the list.");
      } else {
        // delete item by shifting items on the right of the item to the left
        for (int i = row; i < listSize; i++) {
          list[i] = list[i + 1];
        }
        // subtract one from the size (one item deleted from list)
        --listSize;
      }
    } catch (InputMismatchException exception) {
      System.out.println("ERROR: You must enter an integer to delete an item.");
    }
    return listSize;
  }

  public static void display(String[] list, Integer listSize) {
    // loop through the array
    for (int i = 0; i < listSize; i++) {
      // display headings
      if (i == 0) {
        System.out.println("Row  " + list[i]);
      }
      // display grocery list items as a numbered list
      else {
        System.out.println(i + ".   " + list[i]);
      }
    }
  }


  public static void writeToFile(String outputFile, String[] list,
      Integer listSize) {
    // "PrintWriter" is a Class Used To Write to A File.
    PrintWriter fileWriter = null;
    try {
    
      fileWriter = new PrintWriter(outputFile);
    } catch (FileNotFoundException exception) {
      // Print error message.
      // In order to print double quotes("),
      // the escape sequence for double quotes (\") must be used.
      System.out.print("ERROR: File not found for \"");
      System.out.println(outputFile + "\"");
    }
    // if file opened successfully, then below code executes..
    // continue program if writeToFile is not "null"
    if (fileWriter != null) {
      // loop through list (grocery list) and write to file
      for (int i = 0; i < listSize; i++) {
        fileWriter.println(list[i]);
      }
      // REMEMBER: always give feedback to the user!
      System.out.println("Wrote to file \"" + outputFile + "\"");
      // WARNING: don't forget to close the file!
      // will not write to file if not closed!
      fileWriter.close();
    }// end of "if" statement for writeToFile

  }

}// end of class

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