flag/argument in bash alias

I think you are looking for functions.

 function add() {
   local name="$1"
   java -jar vc.jar "${name}"
 }

Add this to your ~/.bashrc or ~/.profile and just call like this;

user@host$ add samplename

Alternatively you can trigger an alias expansion by adding a space or tab character at the end of the alias definition.

alias add='java -jar vc.jar '

(Note the space at the end of definition).

Then just call it normally;

user@host$ add samplename

It should work.

EDIT: As pointed out by @kusalananda you can omit the space and it will still work just fine.

You can try to remove the name flag and set an alias for java -jar vc.jar.

What you want to do:

alias add="java -jar vc.jar"

You now have set an alias. To run it:

add nameofsomethingyouwant

You could also try it with @cevhyruz's solution, but I think this one is simpler.