Synthesis of aryl chlorides/bromides from aryl diazonium salts using cuprous chloride/bromide is called Sandmeyer reaction.
Similarly halogen exchange reaction for the synthesis of alkyl fluorides from alkyl chlorides/bromides by treatment with silver fluoride is known as Swarts reaction.
Schiemann reaction is for the synthesis of aryl fluorides from aryl diazonium salts via a diazonium tetrafluoroborate intermediate.