how do I get the player that used the key in the ClientTickEvent event

[Niinnnnnn]

how do I get the player that used the key in the ClientTickEvent event forge 1.12

[V0idWa1k3r]

Well as the name of the event suggests ClientTickEvent fires on the client. You always have an access to the client player. It's Minecraft.getMinecraft().player.

However I feel that you want to accomplish something else here. Could you please clarify what exactly do you want to accomplish?