A$AP Rocky is staying positive despite going to court on a gun charge that could put him behind bars ... just take a listen to what he had to say after the first day of his gun trial.

The rapper broke his silence Friday after court wrapped, sending a three-word message to his fans.

Rocky tried to sneak out a side door to avoid a throng of reporters and paparazzi ... but TMZ has the first video of him speaking since his trial began.

Seems A$AP seems pretty confident early on ... remember, he also rejected a plea deal that would have put him in jail for six months.

Rocky is accused of firing a gun at a former associate outside a Hollywood hotel in 2021 and he's facing up to 24 years in prison if convicted.

There's a lot at stake but Rocky is taking it all in stride ... at least in front of the cameras.

The first day of trial saw his baby mama Rihanna brought up a few times ... and the first witness to take the stand was a police officer with a famous mother.

Rocky's attorney, Joe Tacopina, also spoke after court and had more to say than his client ... talking to us about a lack of Black people on a jury that's supposed to be made up of Rocky's peers.

A$AP will be back in court next week ... so this is likely all he'll have to say for a few days.