DTO with attributes having public access.

Question

Hi
In my application I'm using Data Trandfer Objects for trasfering data between client and server. It's only used for travfering data and as a client side buffer. Shall I keep all the attributes with public access specifiers?Is it against any concepts?
Example:
public class ResourceDetailsTO {
public String resourceId;
public String lastName;
public String firstName;
public String department;
public String grade;
Any help will be appreciated?

Answer 1

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So my proposal would be a class with a public
constructor, only private attributes and publich
getter methods. Additionally, you should implement
toString to allow easy debugging.
That gets rather tedious when the GUI layer wants to modify a single attribute.
The reason is, that you can easily introduce errors,
if you make all attributes public. Just consider the
following example:
ResourceDetailsTO rdto = receive(); // suppose, this
is some method, which creates a DTO
process(rdto); // here we do something with this DTO
// here you can not know, whether the DTO was modified
by process!!At least in my implementations, I don't try to guess whether it was modified or not. The caller is specifically required to do something different if is modified vs if is not.
And I not sure how this example proves your point. Creating a new object everytime doesn't tell you whether it was modified or not from the original. If you want to track modification then add a setter which sets a flag.
Additionally, if you
implement equals and hashCode, then your DTO could be
a good candidate as a key in a HashMap. Why? The only reason for doing this is to cache the data. So what interface is caching the data? And what happens when the persisted object gets overwritten by another object by another source?
However if the
object is modifyable, then somebody could modify the
attributes, while it is used as a key in some HashMap.Yes, if it used in a hash then modifying it will break it.
But the vast majority will not be used in a hash.
And when it is used in a hash it will not be used as the key.