Java data transfer object naming convention?

Solution 1:

Data Transfer Object classes should follow the name convention defined in the Java Language Specification:

Names of class types should be descriptive nouns or noun phrases, not overly long, in mixed case with the first letter of each word capitalized.
ClassLoader
SecurityManager
Thread
Dictionary
BufferedInputStream
[...]

Suffixing a class name with DTO or Dto is not really meaningful and doesn't tell much what the class itself represents. So it may be better to use names that describe the purpose of your classes.

Here is a non-exhaustive list of name suggestions you could use:

SomeSortOfCommand
SomeSortOfConfiguration
SomeSortOfCredentials
SomeSortOfDetails
SomeSortOfElement
SomeSortOfEvent
SomeSortOfFilter
SomeSortOfHeader
SomeSortOfInput
SomeSortOfInstruction
SomeSortOfItem
SomeSortOfMessage
SomeSortOfMetadata
SomeSortOfOperation
SomeSortOfOutput
SomeSortOfPayload
SomeSortOfProjection
SomeSortOfProperties
SomeSortOfQueryParameter
SomeSortOfQueryResult
SomeSortOfRepresentation
SomeSortOfRequest
SomeSortOfResource
SomeSortOfResponse
SomeSortOfResult
SomeSortOfRow
SomeSortOfSettings
SomeSortOfSpecification
SomeSortOfStatus
SomeSortOfSummary

^{Note 1: Whether acronyms or all capitalized words should be handled as words or not, I guess it's up to you. Check the Java API and you will find some stumbles like ZipInputStream / GZIPInputStream. Both classes are in the same package and the name convention is not consistent. HttpURLConnection doesn't show any consistency with acronyms either.}

^{Note 2: Some names listed above were borrowed from this article written by Richard Dingwall (the original article seems to be no longer available, so here's a cached copy from Web Archive).}

Solution 2:

I generally add 'DTO' to the end of the Class name as well as place all the DTO's in their own package. In your example I would call it com.x.core.dto.CarDTO.