How to note a class of object in object diagram?

Question

How can I add information about the class of the object in object diagram ?

Can I use instance specifications like the ones described here: http://www.uml-diagrams.org/uml-core.html#instance-specification-core

?

Answer 1

Not sure about what you want to draw.

But it you want to have this, for example:

You can use that:

@startuml
sprite $printer8 [15x15/8] {
00098888A110000
000I000088GI000
235I0GOOOW0I532
R00I0GOOOW0I00R
R11HHHHHHHHH11R
S9999999999999S
YaZZZZZZZZZZZaY
0GWWWWWWWWWWWG0
}
object "<u>app-srv-37</u>\nSun Fire Printer <$printer8>" as Foo <<Device>> {
  name = "Dummy"
  id = 123
}
@enduml

See http://www.plantuml.com/plantuml/form?url=JO-v2i9048RxUOeXs8ep2S4LrWL1ZAaYII5UnHgtY9237AA8x-u6pw_vZsdcRwewQmqEh1IjgGNksB-oFn87l0CHJOHbncmjzJdiZH11h-1wVaX154Lh2dtFXRY_lpDH337pyWDp3CdadmGsUlj3Ru22zO-0u07byMpI5XtPALrLmwQ-3Bsn77LgNoHTWOkiDhXwlOxoEq8vg1jSb2LAEJUNB3LAsJc8XSuDJj6PTtb-Sz0ssSbcTZruF040

Answer 2

Just use the " : " in the name of the object, and <u> to underline (but I think that's not necessary in UML2). Here's an example:

left to right direction
object "newPatient:Patient" as p2 {
id : String = "38-545-137"
name = John Doe
gender: Gender = male
}
object "checkAcct:Account" as checkAcct <<interface>>
object "<u>newPatient:</u>" as p
note right 
 Underlining of instances
 is old (UML 1.0)?
end note
object ":Customer" as c

 

Comments

"I think that's not necessary in UML2"

What makes you think so? According to the OMG Unified Modeling Language Version 2.5:
"9.8.4 Notation
An InstanceSpecification is depicted using similar notation to its classifiers , but in place of the Classifier name appears an underlined concatenation of the instance name (if any), a colon (‘:’) and the Classifier name or names. [...]"

The underlining looks mandatory to me...

---

Indeed. I'm now looking at the OMG standard, and I see Figures 11.6 and 11.7 which (to me) illustrate why underlining is important in object diagrams (I was thinking it didn't matter since underlining was removed from participants).

It denotes a concrete object, as opposed to a named instance - it's a subtle but important difference.