Software Development Cross Solution - Index of - Free

focus on functionality
We could fix code...
Now it’s time to figure out what needs to be fixed. At the end of
Chapter 10 you took a look at the Mercury Meals code, and the
prognosis was not good...
394 Chapter 11
// Mercury Meals class continued...
// Follows the Singleton design pattern
public class MercuryMeals
{
public MercuryMeals meallythang;
private Order cO;
{
public boolean submitOrder(Order cO)
try {
MM mm = MM.establish();
mm.su(this.cO);
catch (Exception e)
{ // write out an error message } return false; }
public Order[] getOrdersThatMatchKeyword(String qk)
}}
Order o = new Order[];
try {
o = MM.establish().find(qk, qk);
} catch (Exception e) {
}
return null;
return o;
No documentation on any of this class’s methods!
Something that described what teh methods are
supposed to do would make life a LOT easier for you
Still no documentation...
No wonder the software gave no indication
whether it was working or not (except by just
hanging...) This method swallows all exceptions
that are raised. This is a classic exception
anti-pattern! If an exception gets raised, and
you can’t deal with it locally then pass the
exception up to teh caller so they can at least
do something about it
private String qk = "select * from order-table where keywords like %1;";
public MercuryMeals() {
}
public static MercuryMeals getInstance()
{
}
this.meallythang = new MercuryMeals();
return this.instance;
// TODO Really should document this at some point... TBD
public Order createOrder {
return new Order();}
public MealOption getMealOption(String option)
throws MercuryMealsConnectionException {
}
if (MM.establish().isAnyOptionsForKey(option))
{ return MM.establish.getMealOption(option).[0] };
return null;
No real documentation on the class, other
than the fact that it tries to implement
the Singleton pattern...
Not the most descriptive of
attribute names.
Why is there an Order attribute? Even a
few comments would help.
Surely this should be a constant? And does qk
make any sense as an attribute name?
Why have an explicit constructor
declared that does nothing?
The code indentation is still all
over the place! Making things
very hard to read...
Hang on! This class is supposed to be
implementing the singleton pattern,
but this looks like it creates a new
instance of MercuryMeals every time
this method is called...
throws MercuryMealsConnectionException {
Which qk is being used here? At least
one of them is probably the wrong one
so it’s very unlikely that this code is
going to work at all...
This method seems not to do anything of any real
value at the moment. You could just as easily create
an order without the Mercury Meals class—and as
for the indentation, it’s all over the place.
Hiding exceptions again! The caller of
this method will never have to handle a
MercuryMealsConnectionException or any other
exception because this method is hiding anything
that goes wrong and just returning null again!
Returning null is a bad practice. It’s a better idea to raise
an exception that gives the caller more info to work with.
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All of these problems were
found, and this was only when
you peeked into the first layer
of the Mercury Meals code.