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Java Java Objects Delivering the MVP Applying a Discount Code

Solomon Asiedu-Ofei Jnr
Solomon Asiedu-Ofei Jnr
1,015 Points

im stuck at normalizeDiscountCode java course

So I have used the Regex tester to generate a validation for a string containing only alphabets or $ but my code isn't working. I get an error saying Oops! It looks like Task 1 is no longer passing

Order.java
import java.io.Console;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class Order {
  private String itemName;
  private int priceInCents;
  private String discountCode;
  private String upperCodes;

  private String normalizeDiscountCode(String discountCode) {
    if(discountCode.matches("[a-zA-Z|$]+")){
   throw new IllegalArgumentException("Invalid discount code");
   }

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

  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"
    }

  }
}

1 Answer

andren
andren
28,520 Points

Your regex does indeed identity correct discount codes. But you are telling Java to throw an exception if the discount code matches the regex. You should be doing the opposite. An exception should be thrown if the discount code does not match the regex, since that identifies correct discount codes.

This can be achieved by simply reversing the result of the match method by using the ! operator like this:

import java.io.Console;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class Order {
  private String itemName;
  private int priceInCents;
  private String discountCode;
  private String upperCodes;

  private String normalizeDiscountCode(String discountCode) {
    if(!discountCode.matches("[a-zA-Z|$]+")){
   throw new IllegalArgumentException("Invalid discount code");
   }

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

  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);
  }
}