— Scott McNealy, Sun Microsystems Chairman, President and ceo

generic 
wildcards

---

collections 
with 
generics
you are here
4
575
Alternate syntax for doing the same thing
You probably remember that when we looked at the sort() method, 
it used a generic type, but with an unusual format where the type 
parameter was declared before the return type. It’s just a different way 
of declaring the type parameter, but the results are the same:
public 

 void takeThing(ArrayList

 list)
 
This:
public void takeThing(ArrayList

 list)
 
Does the same thing as this:
there are no
Dumb Questions
Q: 
If they both do the same thing, why would you use 
one over the other?
A: 
It all depends on whether you want to use “T” some-
where else. For example, what if you want the method to 
have two arguments—both of which are lists of a type that 
extend Animal? In that case, it’s more efficient to just declare 
the type parameter once:
Instead of typing:
public 

 void takeThing(ArrayList

 one, ArrayList

 two)
public void takeThing(ArrayList

 one,
ArrayList

 two)
 

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576
 
chapter 16
Exercise
Your job is to play compiler and determine which of 
these statements would compile. But some of this 
code wasn’t covered in the chapter, so you need to 
work out the answers based on what you DID learn, 
applying the “rules” to these new situations. In 
some cases, you might have to guess, but the 
point is to come up with a reasonable answer 
based on what you know so far.
(Note: assume that this code is within a legal class and 
method.)