Java How to Program, Early Objects, 11th Edition

... getPartNumber() {return partNumber;} 
30
31     // get description 
32     public String getPartDescription() {return partDescription;} 
33
34     // get quantity 
35     public int getQuantity() {return quantity;} 
36
37     // get price per item 
38     public double getPricePerItem() {return pricePerItem;} 
39
40     // return String representation of Invoice object
41     @Override 
42     public String toString() { 
43        return String.format("%s: %n%s: %s (%s) %n%s: %d %n%s: $%,.2f", 
44           "invoice", "part number", getPartNumber(), getPartDescription(), 
45           "quantity", getQuantity(), "price per item", getPricePerItem()); 
46     }
47
48     // method required to carry out contract with interface Payable
49     @Override
50     public double getPaymentAmount() {
51        return getQuantity() * getPricePerItem(); ...