Get's nickname of a player

[sayonara2312]

How can I get the nickname of a player who hits with his hand at the time of using the command?

[m00nl1ght]

1. What do you mean by "using the command"? Are you trying to create a command?

2. What do you mean by "a player who hits with his hand"? A player who is interacting with something?

Please explain what you are trying to archieve.

[JimiIT92]

Wheter "using the command" means actually using a command like /something or it means the players does some sort of action (like attacking an entity), you should have an event handler for these events and in that i'm pretty sure you'll find a reference to the player, wich then will give you access to all players informations, like the name in this case.  You can find more about how to intercept an event here on the official Forge documentation. Note that this will give you the basics, for more advanced things you have to figure out by your own