Code works as required in IDE, however, teamTreehouse browser ide rejects.

public class Order {
    private String itemName;
    private int priceInCents;
    private String 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;
    }

    private String normalizeDiscountCode(String dCode) {
      String upperDiscountCode = dCode.toUpperCase();
      char[] cDiscountCode = upperDiscountCode.toCharArray();
      boolean isValid = false;
      for (int i = 0; i < cDiscountCode.length; i++) {
        if((cDiscountCode[i] >=65 && cDiscountCode[i] <= 90) || cDiscountCode[i] == 36) {
          isValid = true;
        } else {
          throw new IllegalArgumentException("Invalid discount code.");
        }
      }
      return upperDiscountCode;
    }

    public void applyDiscountCode(String discountCode) {
      try {
          this.discountCode = normalizeDiscountCode(discountCode);
      } catch(IllegalArgumentException iae){
            System.out.println(iae);
      }
    }
  }

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"
    }

  }
}