将更改的值从一种方法转移到另一种方法

Question

so what I am trying to do it take the Value that I am allowing my BargainCustomer to spend, and get him/her to buy the first car they see in the list under that price. Then take the remaining money and buy whatever features they can. However, I do not remember how to call my value for the remaining money from my other method. Here is my code:

import java.util.ArrayList;

public class BargainCustomer implements Customer
{
   public Car purchase(ArrayList<Car> listOfCars)
   {
       int moneyToSpend = 35000;
       int moneyLeft = 0;
       int indexLocation = 0;
       for (int i = 0; i < listOfCars.size(); i++)
       {
           if (listOfCars.get(i).getBasePrice()<moneyToSpend)
           {
               moneyLeft=moneyToSpend-listOfCars.get(i).getBasePrice();
               indexLocation = i;
           }
       }
       return listOfCars.get(indexLocation);
   } 

   public void upgrade(Car g)
   {
       int featuresMoney = moneyLeft;
       for (int i = 0; i < g.getFeatures().size(); i++)
       {
           moneyLeft-=g.getFeatures().get(i).getCost();
           if (moneyLeft>=0)
           {
               g.getFeatures().get(i).purchase();
           }
       }
   }
}

Ideally the buyer should only buy what they can afford with the remaining money.

Answer 1

depending on your logic, it would be best to just chain the calls:

import java.util.ArrayList;

public class BargainCustomer implements Customer
{
   public Car purchase(ArrayList<Car> listOfCars)
   {
       int moneyToSpend = 35000;
       int moneyLeft = 0;
       int indexLocation = 0;
       for (int i = 0; i < listOfCars.size(); i++)
       {
           if (listOfCars.get(i).getBasePrice()<moneyToSpend)
           {
               moneyLeft=moneyToSpend-listOfCars.get(i).getBasePrice();
               indexLocation = i;
           }
       }
       return upgrade(listOfCars.get(indexLocation), moneyLeft);
   } 

   public void upgrade(Car g, int moneyLeft)
   {
       int featuresMoney = moneyLeft;
       for (int i = 0; i < g.getFeatures().size(); i++)
       {
           moneyLeft-=g.getFeatures().get(i).getCost();
           if (moneyLeft>=0)
           {
               g.getFeatures().get(i).purchase();
           }
       }
   }
}

This will just give you the car with all the features right away, if you need steps in between, you can just use a class variable, or calculate it again. Since you return the car, you can just substract the car price from the moneyToSpend

PS are you sure, int is the right choose for money in your case ? it will not handle comma values. Depending on currency, prices are rarly ever without fractions.