Clean Code

new BooleanArgumentMarshaler()
);
}
..
Listing 14-11
ArgumentMarshaller appended to Args.java
private class ArgumentMarshaler {
private boolean booleanValue = false;
public void setBoolean(boolean value) {
booleanValue = value;
}
public boolean getBoolean() {return booleanValue;}
}
private class BooleanArgumentMarshaler extends ArgumentMarshaler {
}
private class StringArgumentMarshaler extends ArgumentMarshaler {
}
private class IntegerArgumentMarshaler extends ArgumentMarshaler {
}
}

---

214
Chapter 14: Successive Refinement
private void setBooleanArg(char argChar, boolean value) {
booleanArgs.
get
(argChar)
.setBoolean
(value);
}
...
public boolean getBoolean(char arg) {
return falseIfNull(booleanArgs.get(arg).
getBoolean()
);
}
Notice how these changes are in exactly the areas that I mentioned before: the 
parse
,
set
, and 
get
for the argument type. Unfortunately, small as this change was, some of the
tests started failing. If you look carefully at 
getBoolean
, you’ll see that if you call it with
'y
,
'
but there is no 
y
argument, then 
booleanArgs.get('y')
will return 
null
, and the func-
tion will throw a 
NullPointerException
. The 
falseIfNull
function had been used to protect
against this, but the change I made caused that function to become irrelevant.
Incrementalism demanded that I get this working quickly before making any other
changes. Indeed, the fix was not too difficult. I just had to move the check for 
null
. It was
no longer the 
boolean
being
null 
that I needed to check; it was the 
ArgumentMarshaller
.
First, I removed the 
falseIfNull
call in the 
getBoolean
function. It was useless now, so
I also eliminated the function itself. The tests still failed in the same way, so I was confi-
dent that I hadn’t introduced any new errors. 
public boolean getBoolean(char arg) {
return booleanArgs.get(arg).getBoolean();
}
Next, I split the function into two lines and put the 
ArgumentMarshaller
into its own vari-
able named 
argumentMarshaller
. I didn’t care for the long variable name; it was badly
redundant and cluttered up the function. So I shortened it to 
am
[N5]. 
public boolean getBoolean(char arg) {
Args.ArgumentMarshaler