Question

This program wasn’t working when I only had the if/else conditions in the Setters. I got a tip that I have to use them inside the Constructors too. Can someone explain to me.. why?

Another Question: Do you place the if/else statements inside the Constructor or Setters?

//Constructor

   public Invoice(String partNumber, String partDescription, int quantity,
        double pricePerItem) {
    super();
    this.partNumber = partNumber;
    this.partDescription = partDescription;

    if (quantity <= 0)
        quantity = 0;
    else
        this.quantity = quantity;

    if (pricePerItem <= 0)
        pricePerItem = 0.0;
    else
        this.pricePerItem = pricePerItem;
}

//Setters

  public void setQuantity(int quantity) {
    if (quantity <= 0)
        this.quantity = 0;
    else
        this.quantity = quantity;
}

public double getPricePerItem() {
    return pricePerItem;
}

public void setPricePerItem(double pricePerItem) {

    if (pricePerItem != 0.0)
        this.pricePerItem = 0.0;

    else
        this.pricePerItem = pricePerItem;
}

Answer 1

Your best bet is to put the if/else statements in the setters and use the setters from within the constructor. That way you have your logic in exactly one place and it’s much easier to maintain.