I can't figure out why I get the NullPointerException on Line 223. Would appreciate any help whatsoever.

Sorry about the spacing below. Some of the code appears messy. Toggle Plain Text and it should look better.

/* Section 1: Import Statements. Imports the Scanner class and the IO Package. */

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

/* Section 2: Class ReadFiles, contains the methods to open, read and close all the files to be read by the program. */

class ReadFiles {
	String [] codes = new String[99];
	String [] description = new String[99];
	int [] pricesAndTax = new int[99];
	int [] weight = new int[99];
	int j = 0;

	private Scanner readCodes;
	private Scanner readDesc;
	private Scanner readPAndT;
	private Scanner readWeight;

	/* Section : Methods to open, read and close the 'codes.txt' file. */

	public void openCodesFile() {
		try {
			readCodes = new Scanner(new File("C:/Users/Carlo/Desktop/Files/codes.txt"));
		} catch (Exception e) {
			System.out.println("Could not locate the data file!");
		}
	}

	public void readCodesFile() {

		while(readCodes.hasNext()) {
			codes[j] = readCodes.nextLine();
			//System.out.println(codes[i]);
			j++;
		}
	}

	public void closeCodesFile() {
		readCodes.close();
	}

	/* Section : Methods to open, read and close the 'description.txt' file. */

	public void openDescFile() {
		try {
			readDesc = new Scanner(new File("C:/Users/Carlo/Desktop/Files/description.txt"));
		} catch (Exception e) {
			System.out.println("Could not locate the data file!");
		}
	}

	public void readDescFile() {

		while(readDesc.hasNext()) {
			description[j] = readDesc.nextLine();
			//System.out.println(description[i]);
			j++;
		}
	}

	public void closeDescFile() {
		readDesc.close();
	}

	/* Section : Methods to open, read and close the 'priceAndTax.txt' file. */

	public void openPAndTFile() {
		try {
			readPAndT = new Scanner(new File("C:/Users/Carlo/Desktop/Files/priceAndTax.txt"));
		} catch (Exception e) {
			System.out.println("Could not locate the data file!");
		}
	}

	public void readPAndTFile() {

		while(readPAndT.hasNext()) {
			pricesAndTax[j] = readPAndT.nextInt();
			//System.out.println(pricesAndTax[i]);
			j++;
		}
	}

	public void closePAndTFile() {
		readPAndT.close();
	}

	/* Section : Methods to open, read and close the 'weight.txt' file. */

	public void openWeightFile() {
		try {
			readWeight = new Scanner(new File("C:/Users/Carlo/Desktop/Files/weight.txt"));
		} catch (Exception e) {
			System.out.println("Could not locate the data file!");
		}
	}

	public void readWeightFile() {

		while(readWeight.hasNext()) {
			weight[j] = readWeight.nextInt();
			//System.out.println(weight[i]);
			j++;
		}
	}

	public void closeWeightFile() {
		readWeight.close();
	}
}

/* Section : Class NewHardware. Contains the main method. */

public class NewHardware {
	public static void main(String[] args) {
		/* Instances of the ReadFiles class. */

		ReadFiles codesRead = new ReadFiles();
		ReadFiles descRead = new ReadFiles();
		ReadFiles pAndTRead = new ReadFiles();
		ReadFiles weightRead = new ReadFiles();

		/* Section : Scanner object for user input. */

		Scanner in = new Scanner(System.in);

		String userName;
		String address1;
		String address2;
		String city;
		String country;
		String postalCode;
		String buyerNew;
		int i = 1000;
		String output = "";
		String [] userCode = new String[i];
		char dolSymb = '$';
		float weightTotal = 0f;
		float weightCalc = 0f;
		int [] userQuantity = new int[i];
		int [] userPrice = {0, 0, 0, 0, 0, 0, 0, 0, 0};
		int [] orderLimit = {0, 0, 0, 0, 0, 0, 0, 0, 0};
		int userPreWithTax = 0;
		int userTotal = 0;
		int userPreTotal = 0;
		int userShipping = 0;
		int inputCount = 0;

		/* Section : Methods from the ReadFiles class being called here to be executed. */

		/* Section : All the 'open...' methods. */

		codesRead.openCodesFile();
		descRead.openDescFile();
		pAndTRead.openPAndTFile();
		weightRead.openWeightFile();

		/* Section : All the 'read...' methods. */

		codesRead.readCodesFile();
		descRead.readDescFile();
		pAndTRead.readPAndTFile();
		weightRead.readWeightFile();

		/* Section : Printing the welcome statement and the catalog. */

		System.out.printf("\n\n%55s", "**WELCOME TO THE HARDWARE STORE**\n");
		System.out.printf("%56s", "=================================\n\n");
		System.out.printf("%-10s%-40s%-15s%-10s\n", "CODE", "DESCRIPTION", "WEIGHT(grams)", "PRICE\n");

		/* Section : A for-loop to print out the catalog. Makes use of the welCount variable to go through all the product information. */

		for (int welCount = 0; welCount < 9; welCount++) {
			System.out.printf("%-10s%-40s%-15d%-1s%d.%02d\n", codesRead.codes[welCount], descRead.description[welCount], weightRead.weight[welCount], dolSymb, pAndTRead.pricesAndTax[welCount]/100, pAndTRead.pricesAndTax[welCount]%100);
		}

		/* Section : Loops to take customer input. */


		i = 0;
		do {
			System.out.println("\n\nPLEASE ENTER YOUR ORDER:");
			System.out.print("\nNAME: ");
			userName = in.nextLine();
			System.out.print("\nADDRESS Line 1: ");
			address1 = in.nextLine();
			System.out.print("\nADDRESS Line 2: ");
			address2 = in.nextLine();
			System.out.print("\nCITY: ");
			city = in.nextLine();
			System.out.print("\nCOUNTRY: ");
			country = in.nextLine();
			System.out.print("\nPOSTAL CODE: ");
			postalCode = in.nextLine();
			System.out.println();

			while (true) {

				System.out.print("CODE (X to QUIT):");
				userCode[i] = in.nextLine();

				if (userCode[i].equalsIgnoreCase("x")) {
					break;
				}

				System.out.print("QUANTITY: ");
				userQuantity[i] = in.nextInt();
				in.nextLine();

				if (userCode[i].equalsIgnoreCase(codesRead.codes[0]) && userQuantity[i] >= 1) {
					orderLimit[0] += userQuantity[i];
					if (orderLimit[0] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[0] = 0;
					} else {
					userPrice[0] += userQuantity[i]*pAndTRead.pricesAndTax[0];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[0], "\n", descRead.description[0], " @ ", dolSymb, pAndTRead.pricesAndTax[0]/100, pAndTRead.pricesAndTax[0]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[0]*userQuantity[i])/100, (pAndTRead.pricesAndTax[0]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[0];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[1]) && userQuantity[i] >= 1) {
					orderLimit[1] += userQuantity[i];
					if (orderLimit[1] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[1] = 0;
					} else {
					userPrice[1] += userQuantity[i]*pAndTRead.pricesAndTax[1];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[1], "\n", descRead.description[1], " @ ", dolSymb, pAndTRead.pricesAndTax[1]/100, pAndTRead.pricesAndTax[1]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[1]*userQuantity[i])/100, (pAndTRead.pricesAndTax[1]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[1];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[2]) && userQuantity[i] >= 1) {
					orderLimit[2] += userQuantity[i];
					if (orderLimit[2] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[2] = 0;
					} else {
					userPrice[2] += userQuantity[i]*pAndTRead.pricesAndTax[2];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[2], "\n", descRead.description[2], " @ ", dolSymb, pAndTRead.pricesAndTax[2]/100, pAndTRead.pricesAndTax[2]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[2]*userQuantity[i])/100, (pAndTRead.pricesAndTax[2]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[2];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[3]) && userQuantity[i] >= 1) {
					orderLimit[3] += userQuantity[i];
					if (orderLimit[3] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[3] = 0;
					} else {
					userPrice[3] += userQuantity[i]*pAndTRead.pricesAndTax[3];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[3], "\n", descRead.description[3], " @ ", dolSymb, pAndTRead.pricesAndTax[3]/100, pAndTRead.pricesAndTax[3]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[3]*userQuantity[i])/100, (pAndTRead.pricesAndTax[3]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[3];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[4]) && userQuantity[i] >= 1) {
					orderLimit[4] += userQuantity[i];
					if (orderLimit[4] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[4] = 0;
					} else {
					userPrice[4] += userQuantity[i]*pAndTRead.pricesAndTax[4];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[4], "\n", descRead.description[4], " @ ", dolSymb, pAndTRead.pricesAndTax[4]/100, pAndTRead.pricesAndTax[4]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[4]*userQuantity[i])/100, (pAndTRead.pricesAndTax[4]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[4];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[5]) && userQuantity[i] >= 1) {
					orderLimit[5] += userQuantity[i];
					if (orderLimit[5] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[5] = 0;
					} else {
					userPrice[5] += userQuantity[i]*pAndTRead.pricesAndTax[5];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[5], "\n", descRead.description[5], " @ ", dolSymb, pAndTRead.pricesAndTax[5]/100, pAndTRead.pricesAndTax[5]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[5]*userQuantity[i])/100, (pAndTRead.pricesAndTax[5]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[5];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[6]) && userQuantity[i] >= 1) {
					orderLimit[6] += userQuantity[i];
					if (orderLimit[6] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[6] = 0;
					} else {
					userPrice[6] += userQuantity[i]*pAndTRead.pricesAndTax[6];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[6], "\n", descRead.description[6], " @ ", dolSymb, pAndTRead.pricesAndTax[6]/100, pAndTRead.pricesAndTax[6]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[6]*userQuantity[i])/100, (pAndTRead.pricesAndTax[6]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[6];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[7]) && userQuantity[i] >= 1) {
					orderLimit[7] += userQuantity[i];
					if (orderLimit[7] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[7] = 0;
					} else {
					userPrice[7] += userQuantity[i]*pAndTRead.pricesAndTax[7];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[7], "\n", descRead.description[7], " @ ", dolSymb, pAndTRead.pricesAndTax[7]/100, pAndTRead.pricesAndTax[7]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[7]*userQuantity[i])/100, (pAndTRead.pricesAndTax[7]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[7];
					i++;
					}
				}
				if (userCode[i].equalsIgnoreCase(codesRead.codes[8]) && userQuantity[i] >= 1) {
					orderLimit[8] += userQuantity[i];
					if (orderLimit[8] > 100) {
						System.out.println("Sorry, you can only order 100 of a particular item.");
						orderLimit[8] = 0;
					} else {
					userPrice[8] += userQuantity[i]*pAndTRead.pricesAndTax[8];
					output += String.format("%d%s%s%s%s%s%s%d.%02d%s%s%d.%02d\n", userQuantity[i], " x ", codesRead.codes[8], "\n", descRead.description[8], " @ ", dolSymb, pAndTRead.pricesAndTax[8]/100, pAndTRead.pricesAndTax[8]%100, ": ", dolSymb, (pAndTRead.pricesAndTax[8]*userQuantity[i])/100, (pAndTRead.pricesAndTax[8]*userQuantity[i])%100);
					weightTotal += userQuantity[i]*weightRead.weight[8];
					i++;
					}
				}
				weightCalc = weightTotal/250;
				userShipping = (int)Math.ceil(weightCalc)*100;
				userPreTotal = (userPrice[0] + userPrice[1] + userPrice[2] + userPrice[3] + userPrice[4] + userPrice[5] + userPrice[6] + userPrice[7] + userPrice[8] + userShipping);
				userPreWithTax = (userPreTotal * pAndTRead.pricesAndTax[9])/100;
				userTotal = userPreTotal + userPreWithTax;
			}
			System.out.printf("\n%s\n", "INVOICE FOR ORDER:");
			System.out.printf("%s\n\n", "------------------");
			System.out.printf("%s\n", userName);
			System.out.printf("%s\n", address1);
			System.out.printf("%s\n", address2);
			System.out.printf("%s\n", city);
			System.out.printf("%s\n", country);
			System.out.printf("%s\n", postalCode);
			System.out.printf("\n\n\n%s\n", output);
			System.out.printf("%s%.2f%s\n", "TOTAL WEIGHT: ", weightTotal, " grams.");
			System.out.printf("\n%s%.2f%s%s%d.%02d\n", "SHIPPING COST for ", weightTotal, " grams: ", dolSymb, userShipping/100, userShipping%100);
			System.out.printf("\n%s%s%d.%02d\n", "TOTAL WITH SHIPPING: ", dolSymb, userPreTotal/100, userPreTotal%100);
			System.out.printf("\n%s%s%d.%02d\n", "VAT @ 20%: ", dolSymb, userPreWithTax/100, userPreWithTax%100);
			System.out.printf("\n%s%s%d.%02d\n\n\n", "TOTAL: ", dolSymb, userTotal/100, userTotal%100);
			System.out.printf("%55s\n", "THANK YOU FOR SHOPPING AT HARDWARE STORE!");
			System.out.printf("%55s\n", "=========================================");

			i = 0;
			userTotal *= i;
			userPrice[0] *= i; userPrice[1] *= i; userPrice[2] *= i; userPrice[3] *= i; userPrice[4] *= i; userPrice[5] *= i; userPrice[6] *= i; userPrice[7] *= i; userPrice[8] *= i;
			output = "";
			orderLimit[0] *= i; orderLimit[1] *= i; orderLimit[2] *= i; orderLimit[3] *= i; orderLimit[4] *= i; orderLimit[5] *= i; orderLimit[6] *= i; orderLimit[7] *= i; orderLimit[8] *= i;
			weightTotal *= i;

			System.out.printf("\n\n%s", "ANOTHER CUSTOMER? (Y or N): ");
			buyerNew = in.nextLine();
		} while (!buyerNew.equalsIgnoreCase("n"));



		/* Section : All the 'close...' methods. */

		codesRead.closeCodesFile();
		descRead.closeDescFile();
		pAndTRead.closePAndTFile();
		weightRead.closeWeightFile();
	}
}

Line 223 as in
(userCode.equalsIgnoreCase(codesRead.codes[1]) && userQuantity >= 1) {
the first question is which of those is null? Immediately before that line print all those variables to see which is null (personally I suspect userCode)
When you know which it is, you should be able to see why

Thanks, that helped. I just needed to add 'else' to all the subsequent if statements.

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