Help with checking if this string has only letters or $.

Question

In this assignment, I am trying to throw an exception if the input contains anything other than letters or the character '$'. Am I on the right track with how I'm trying to code this?

  private String normalizeDiscountCode(String discountCode) {
    char[] discountArray = discountCode.toCharArray();
    char[] validCharacters = ("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$").toCharArray();
    if (!validCharacters.indexOf(discountArray)) {
      throw new IllegalArgumentException("Invalid Discount Code");
    }

What I'm thinking this should do is throw the exception if it doesn't find the characters in discountArray in the validCharacters array. Obviously I'm wrong, but am I attacking this question properly and doing it wrong or should I try a completely different approach.

If possible, I'd prefer not to be handed the answer, so much as directed towards it. Thank you so much!

Order.java

public class Order {
  private String itemName;
  private int priceInCents;
  private String discountCode;
  boolean isAcceptableCharacter = false;

  private String normalizeDiscountCode(String discountCode) {
    char[] discountArray = discountCode.toCharArray();
    char[] validCharacters = ("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$").toCharArray();
    if (!validCharacters.indexOf(discountArray)) {
      throw new IllegalArgumentException("Invalid Discount Code");
    }

    discountCode = discountCode.toUpperCase();
    return discountCode;
  }

  public Order(String itemName, int priceInCents) {
    this.itemName = itemName;
    this.priceInCents = priceInCents;
  }

  public String getItemName() {
    return itemName;
  }

  public int getPriceInCents() {
    return priceInCents;
  }

  public String getDiscountCode() {
    return discountCode;
  }

  public void applyDiscountCode(String discountCode) {
    this.discountCode = normalizeDiscountCode(discountCode);
  }
}

Example.java

public class Example {

  public static void main(String[] args) {
    // This is here just for example use cases.

    Order order = new Order(
            "Yoda PEZ Dispenser",
            600);

    // These are valid.  They are letters and the $ character only
    order.applyDiscountCode("abc");
    order.getDiscountCode(); // ABC

    order.applyDiscountCode("$ale");
    order.getDiscountCode(); // $ALE


    try {
      // This will throw an exception because it contains numbers
      order.applyDiscountCode("ABC123");
    } catch (IllegalArgumentException iae) {
      System.out.println(iae.getMessage());  // Prints "Invalid discount code"
    }
    try {
      // This will throw as well, because it contains a symbol.
      order.applyDiscountCode("w@w");
    }catch (IllegalArgumentException iae) {
      System.out.println(iae.getMessage());  // Prints "Invalid discount code"
    }

  }
}

Answer 1 · 2017-05-02T20:48:48Z

May 2, 2017 8:48pm

Try checking if the discount code passed in as a parameter contains any invalid characters. If it does, throw the exception. If not, continue. Check this documentation on Strings if you need any help: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html

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Jebadeiah Jones

Jebadeiah Jones

Help with checking if this string has only letters or $.

1 Answer

Tyler Combs

Tyler Combs