Table method with the If statement in Java

I am a graduate student learning the Java program. As a homework assignment, we are to do the following:

• Create a menu of items where the user can input choices into an array
• Create a method that figures out the prices of the items chose and return the sum

Right now, my output shows that the total being returned from the method is actually adding all the prices in the if statement instead of coordinating them with the user input array that was copied (see example output on bottom). We have not touched upon anything further than the standard array (no ArrayList or other methods). Please offer any advice, I will do my best to figure it out.

import java.util.Arrays;
import java.util.Scanner;

public class Online_Purchasing_HW6 {

public static final int ARRAY_LENGTH = 10;      //Length of the array 

public static void main(String[] args) {
     Scanner input = new Scanner(System.in); //Reads user input
     int[] naMenuChoice = new int [ARRAY_LENGTH];   //Array for items chosen
     String[] naMenu = new String [ARRAY_LENGTH];   //Array for menu items
     int[] naItemPrice = new int [9];  //Array for item prices
    String sCustomerName;         //String for customer's name
    int nChoice = 0;             //Option chosen in menu by user/Used as Index
    int nSum = 0;                //Sum of items chosen
    double dTotalPrice = 0;      //Total price plus taxes
    double dTaxes = 0;           //Total taxes to be applied to total

    //Declare Constants
    final int SENTINEL = 10;               //Used to end loop
    final double SALES_TAX = 0.065;         //Sales tax to be used

    //Choices for menu denoted by strings
    String sChoice1 = "1. Smartphone" + "\t" + "\t" + "$249";
    String sChoice2 = "2. Smartphone Case" + "\t" + "$39";
    String sChoice3 = "3. PC Laptop" + "\t" + "\t" + "$1149";
    String sChoice4 = "4. Tablet" + "\t" + "\t" + "$349";
    String sChoice5 = "5. Tablet Case" + "\t" + "\t" +  "$49";
    String sChoice6 = "6. eReader" + "\t" + "\t" + "$119";
    String sChoice7 = "7. PC Desktop" + "\t" + "\t" + "$899";
    String sChoice8 = "8. LCD Monitor" + "\t" + "\t" + "$299";
    String sChoice9 = "9. Laser Printer" + "\t" + "$399";
    String sChoice10 = "10. Complete my order";

    //Prompt user for name
    System.out.print("Please enter your name: ");

    //Read customer's name
    sCustomerName = input.nextLine();

    //Menu of items for purchase
     System.out.print("\n");
     System.out.println("Best Purchase Products");
     System.out.println(sChoice1);
     System.out.println(sChoice2);
     System.out.println(sChoice3);
     System.out.println(sChoice4);
     System.out.println(sChoice5);
     System.out.println(sChoice6);
     System.out.println(sChoice7);
     System.out.println(sChoice8);
     System.out.println(sChoice9);
     System.out.println(sChoice10);

   //Prompt user for item selection
    System.out.print("Please select an item from the menu above: ");

    naMenuChoice[nChoice] = input.nextInt();

        //Loop to read integers from user
         while (naMenuChoice[nChoice] != SENTINEL) {         

        //adds 1 everytime more than one item is chosen by the user
        nChoice++;       

        //Prompt user for another choice since he/she has not chosen option "10"
        System.out.print("Please select another item from the menu above: ");
        naMenuChoice[nChoice] = input.nextInt(); 

         } //end of while loop

    System.out.print(Arrays.toString(naMenuChoice));
    //If option 10 if chosen, the loop will end with this message
    System.out.println("\n" + "Thank you for ordering with Best Purchase, " + sCustomerName );

    //call calculateTotalPrice method passing Array
    nSum = nCalculatePrice(naMenuChoice);

    //Formulas

    //Sales Tax
    dTaxes = SALES_TAX * nSum;

    //Total Amount Due
    dTotalPrice = dTaxes + nSum;

    System.out.println("Total items ordered: " + nChoice);
    System.out.println("Price of items ordered: $" + nSum);
    System.out.println("Sales tax: $" + dTaxes);
    System.out.println("Total amount due: $" + dTotalPrice);
}//end of main method

//Method for calculating price
public static int nCalculatePrice(int[] naChoicesToPrice){
int nTotalPrice = 0; //int value to return
int nIndex = 0; //used as counter
int nItemPrice = 0; //used to assign price of items
int[] naAddedPrices = new int[ARRAY_LENGTH]; //new array for assigning prices

//For loop to sum up all entries from naItemPrice array
for (nIndex = 0; nIndex < ARRAY_LENGTH; nIndex++){
    naAddedPrices[nIndex] = naChoicesToPrice[nIndex];
 //end of For Loop

    if (nIndex == 1) {
         nItemPrice = 249;
         nTotalPrice += nItemPrice;}
    if (nIndex == 2) {
        nItemPrice = 39;
        nTotalPrice += nItemPrice;}
    if (nIndex == 3) {
        nItemPrice = 1149;
        nTotalPrice += nItemPrice;}
    if (nIndex == 4) {
        nItemPrice = 349;
        nTotalPrice += nItemPrice;}
    if (nIndex == 5) {
        nItemPrice = 49;
        nTotalPrice += nItemPrice;}
    if (nIndex == 6) {
        nItemPrice = 119;
        nTotalPrice += nItemPrice;}
    if (nIndex == 7) {
        nItemPrice = 899;
        nTotalPrice += nItemPrice;}
    if (nIndex == 8) {
        nItemPrice = 299;
        nTotalPrice += nItemPrice;}
    if (nIndex == 9) {
        nItemPrice = 399;
        nTotalPrice += nItemPrice;}
} //end of for loop

return nTotalPrice;
}//end of naCalculatePrice method

}//end of class

Corresponding output for the program is:

Please enter your name: John Smith

    Best Purchase Products
1. Smartphone       $249
2. Smartphone Case  $39
3. PC Laptop        $1149
4. Tablet       $349
5. Tablet Case      $49
6. eReader      $119
7. PC Desktop       $899
8. LCD Monitor      $299
9. Laser Printer    $399
10. Complete my order
Please select an item from the menu above: 9
Please select another item from the menu above: 10
[9, 10, 0, 0, 0, 0, 0, 0, 0, 0]
Thank you for ordering with Best Purchase, John Smith
Total items ordered: 1
Price of items ordered: $3551
Sales tax: $230.815
Total amount due: $3781.815

As you can see, I chose only one item from the menu but it adds up all the prices. I've been on this assignment for 2 weeks so far and I'm growing desperate. I've read most articles on this site pertaining to this subject, read many articles on just methods and arrays, respectively and still can't formulate a working program.Any help would be appreciated.

Nice work so far.

In your for loop to sum up, you have to look into naMenuChoices to see what the customer has ordered. Remember, you may find a 0 or a 10 there, in which case you should not add anything to the sum. Good luck, you’re not that far from your goal.

You may want to make yourself a class for the product/items like

public class Product {
    private String itemText;
    private int itemPrice;

    public Product(String itemText, int itemPrice) {
        this.itemText = itemText;
        this.itemPrice = itemPrice;
    }

    public int getItemPrice() {
        return itemPrice;
    }

    @Override
    public String toString() {
        return itemText + "\t\t$" + itemPrice;
    }
}

Fill 9 objects of this class into an array, use them for building the sChoice Strings and use it instead of the naItemPrice array. Modify my code to your needs. It should give a better overview of the code. And eliminate the risk of accidentally charging another price from the customer than the one announced.