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Java Java Objects Delivering the MVP Applying a Discount Code

Talal Alghamdi
Talal Alghamdi
1,603 Points

How to verify letters only or the $ character are used in a string?

In the previous lesson we used the Charcter.isLetter method. I searched online for a similar method for a string, but couldn't find anything useful.

Order.java
public class Order {
private String itemName;
private int priceInCents;
private String discountCode;

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

              private  String normalizeDiscountCode (String code){
              code = code.toUpperCase();
              if (! Character.isLetter(code)){ // Can't convert char to string.
              throw new IllegalArgumentExceotion ("Invalid discount code.");
              }
              return code; 
              }


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"
    }

  }
}

1 Answer

Florian Tönjes
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Florian Tönjes
Full Stack JavaScript Techdegree Graduate 50,856 Points

Hi Talal,

you can use the "toCharArray()" method of the String to get an array of chars. You can then loop over this array and check if the current char is a letter or a "$".

Kind Regards, Florian