Virtual Vending Machine

Question

So far I have written this code for a virtual vending machine:

public class VirtualVender {
        public static void main(String[] args){
        int MILK_CHOCOLATE = 01;
        int DARK_CHOCOLATE = 02;
        int LIGHT_CHOCOLATE = 03;
        int COOKIE_CHOCOLATE = 04;
        int SELECTION;
        System.out.println("********************");
        System.out.println("Vending Machine");
        System.out.println("Enter Your Selection");
        Scanner input = new Scanner(System.in);
        SELECTION = input.nextInt();
        System.out.println("********************");
    }
}

So from my understanding the user input should now be stored in SELECTION, but how do I get SELECTION to bring up MILK_CHOCOLATE if I inputted 01? if you need a more indepth question just respond and I'll try and explain my question better.

Thanks for any help!

You compare them with an `if` or `switch`. Or you use a `Map` to do it for you. Also read [this](http://stackoverflow.com/questions/565634/integer-with-leading-zeroes) for your `0` prefixed ints. — Sotirios Delimanolis, Aug 27 '13 at 18:09
For what it's worth, if you want the user to actually enter in the leading zeroes, you'll have to compare strings, not numbers. — Dennis Meng, Aug 27 '13 at 18:10

score 1 · Answer 1 · answered Aug 27 '13 at 18:14

There are a lot of different ways to do it. Here's one:

if (SELECTION == MILK_CHOCOLATE) {
  System.out.println("Please enjoy your milk chocolate.");
}

By the way, the convention is to use ALL_UPPERCASE for constants, that is, values that will stay the same throughout the life of your program. So while MILK_CHOCOLATE is a constant, the user's selection isn't. You should name that variable selection instead. The Java compiler doesn't care, but the code will be easier for other programmers to read.

It's also good habit to start declaring things as `final` if you know ahead of time that the value should never change. Eg, `final int MILK_CHOCOLATE 01` — user1231232141214124, Aug 27 '13 at 18:21

score 1 · Answer 2 · answered Aug 27 '13 at 18:21

Declare an enum that defines your flavours and associated integer values:

public enum Flavour {
  MILK_CHOCOLATE(1), 
  DARK_CHOCOLATE(2), 
  LIGHT_CHOCOLATE(3), 
  COOKIE_CHOCOLATE(4);

  private final int value;

  private Flavour(int value) {
    this.value = value;
  }

  public static Flavour fromValue(int value) {
    for (Flavour f : values()) {
      if (f.value == value) {
        return f;
      }
    }
    return null;
  }

  // Add a toString() method if you want to better control
  // how the flavour names are printed
}

Then use your enum to validate the user input values:

System.out.println("********************");
System.out.println("Vending Machine");
System.out.println("Enter Your Selection");

// Use try-with-resources to close Scanner:
try (Scanner input = new Scanner(System.in)) {
  int selection = input.nextInt();

  Flavour flavour = Flavour.fromValue(selection);

  if (flavour != null) {
    System.out.println(flavour);
  } else {
    System.out.println("Bad selection!");
  }
  System.out.println("********************");
}

progrenhard · Answer 3 · 2013-08-27T18:25:36.053

0

Use cases man.

String output; 
switch (selection) {
            case 1:  output = "milk chocolate";
                     break;
            case 2:  output = "dark chocolate";
                     break;
            ..

            default: output = "Not a correct value."
}

I believe they resemble the vending machine problem or circuits in general the best.

edited Aug 27 '13 at 18:25

answered Aug 27 '13 at 18:18

progrenhard

2,333
2
14
14

Virtual Vending Machine

3 Answers3