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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