Benefits of Generics

One beneit of using generic classes should now be obvious:
improved correctness. Incorrect types of objects can no longer
be entered into a list. While erroneous attempts to insert
an element could previously be detected only during testing
(and testing can never be complete), they are now detected at
compile time, and type correctness is guaranteed. In addition,
if there is such an error, it will be reported at the point of the
incorrect insertion—not at the
point of retrieving the element,
which is far removed from the
actual error location.
There is, however, a second
beneit: readability. By
explicitly specifying the element
type of collections,
you are providing useful information to human readers of
your program as well. Explicitly saying what type of element
a collection is intended for can make life easier for a
maintenance programmer.

Struts2 Points to remember about “field-validator” nodes

Each field can have one or more “field-validator” nodes

Each fields validators are executed in the order they are defined

Each field validator has a “short-circuit” attribute; if this

is true and the validation fails, all further validations are

skipped and a failed result returned for the field

The message node can include a “key” attribute which

looks up the message to display to the user from a

message bundle; the value of the node is then used if no

message bundle key exists

Validator configuration information (such as min and

max) as well as values from the value stack can be used

in the validation message by placing the value between

the tokens “${“ and “}”

Validators can have a scope of either “field” or

“expression”; expression validators can work across

multiple fields

BENEFITS OF GENERICS

One beneit of using generic classes should now be obvious:
improved correctness. Incorrect types of objects can no longer
be entered into a list. While erroneous attempts to insert
an element could previously be detected only during testing
(and testing can never be complete), they are now detected at
compile time, and type correctness is guaranteed. In addition,
if there is such an error, it will be reported at the point of the
incorrect insertion—not at the
point of retrieving the element,
which is far removed from the
actual error location.
There is, however, a second
beneit: readability. By
explicitly specifying the element
type of collections,
you are providing useful information to human readers of
your program as well. Explicitly saying what type of element
a collection is intended for can make life easier for a
maintenance programmer.