juice => countable or uncountable?

[xiaoen]

Hi,
Dictionaries say that "juice" is countable and uncountable.

I am confused now because I don't know when I can use article "a" with it and when I can not.

Can you help me with this please?

 

[Mori]

It's uncountable unless you're talking about different kinds of juice, e.g. a selection/variety of fruit juices, or a container of juice, e.g. Two orange juices (=Two glasses of orange juice), please.

 

[Raymott]

It can be countable in normal circumstances in AusE.

At a social function:
Serving person at counter: "We have coffee, tea, and juice."
Me: "I'll have a juice, please."/"Give us a juice, thanks."