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Java Java Objects Delivering the MVP Applying a Discount Code

Julie Maya
Julie Maya
14,666 Points
Posted by Julie Maya
Julie Maya
14,666 Points

Get stuck on missing return statement;

In the normalizeDiscountCode verify that only letters or the $ character are used. If any other character is used, throw a IllegalArgumentException with the message Invalid discount code.

Here's my code to the challenge task 2. I kept getting the message saying I miss a return statement after if...

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

  private String normalizeDiscountCode(String discountCode) {
    for (char letter: discountCode.toCharArray()) {
      if ( ! Character.isLetter(letter) && letter != '$') {
        throw new IllegalArgumentException("Invalid discount code.");
      } 
      return discountCode.toUpperCase();
    }

  }

  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);
  }

}

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

The problem is that your return statement is inside of your for loop, this causes two issues. The first issue is that your code will always return after looping once, which means that you won't actually end up checking all of the characters in the discountCode. The second issue is that in Java a method needs to always return a value no matter what happens, since your return statement is inside a for loop which might not always run you could end up in a situation where the method does not return anything. That is what causes you to get an error about you missing a return statement.

Java requires that you always have a return statement outside of loops, the same is also true of if statements, unless you also have an accompanying else statement that also returns.

Both of your issues can be solved by simply moving your return statement so that it is outside of your for loop, like this:

private String normalizeDiscountCode(String discountCode) {
    for (char letter: discountCode.toCharArray()) {
        if ( ! Character.isLetter(letter) && letter != '$') {
          throw new IllegalArgumentException("Invalid discount code.");
        } 
    }
    return discountCode.toUpperCase();
}
Julie Maya
Julie Maya
14,666 Points
Julie Maya
Julie Maya
14,666 Points

I see. I shouldn't put return statement within the loop. Otherwise, I can't finish checking every letter in discountCode. Thank you Andren!

andren
andren
28,558 Points
andren
andren
28,558 Points

Indeed, since return ends execution of the method (and therefore the for loop as well) you never want to have a return statement inside of a loop, unless you want it to exit early for some reason.