将我的用户输入传递给方法时，如何获取用户输入以访问我的ArrayList

Question

Here's the code I have so far. This is the error I get for line 58

incompatible types required: ArrayList found:
VendProduct

(Alt-Enter shows hints)

//A vending machine to dispense multiple products

package newvendingmachine;

import java.util.ArrayList;
import java.util.Scanner;

//Tony Moore 

public class NewVendingMachine{
    //Set class data
    static String[] product = {"Chips", "M&Ms", "Peanuts", "Popcorn", "Snickers"};
    static Float[] cost = {.50f, .75f, .75f, .75f, .90f};
    static Integer[] inventory = {20, 20, 20, 20, 20};

    /** 
    * @param args the command line arguments
    */
    public static void main(String[] args) {
        ArrayList<VendProduct> vp = new ArrayList<>();
        for (int idx=0; idx<product.length; idx++) {
            vp.add(new VendProduct());
        }

        //Accept user input
        Scanner input = new Scanner(System.in);   
        int userInput;

        while (true) {
            // Display menu graphics

            System.out.println(" Options: Press your selection then press enter ");
            System.out.println(" 1. "+product[0]+" ");
            System.out.println(" 2. "+product[1]+" ");
            System.out.println(" 3. "+product[2]+" ");
            System.out.println(" 4. "+product[3]+" ");
            System.out.println(" 5. "+product[4]+" ");
            System.out.println(" 6. Quit ");


            userInput = input.nextInt(); 

            if (userInput <1 || userInput >6) {
                System.out.println("Please make a vaild selection");    
            }

            if (userInput >=1 || userInput <=6) {
                vp = (VendProduct)vp.get(userInput-1);
                vp.buyProduct();         
            }

            if (userInput == 6) {
                System.out.println("Thanks, and come back soon");
                break;
            }
        }   
    }
}

Answer 1

vp = (VendProduct)vp.get(userInput-1);

vp is an ArrayList of VendProduct, but you're trying to set it to just one VendProduct...

You should create a variable of the type VendProduct and use that, like this:

 VendProduct product = vp.get(userInput-1);
 product.buyProduct();

You could also do vp.get(userInput-1).buyProduct(); directly in one line. That's up to you. Using two lines usually makes the code a bit cleaner and easier to read.