Minecraft] Java data from the id.yml read?

I have now written a Minecraft plugin, which stores an ID in id.yml.

So for example. So:

The name: ID

I have now created a command ("/ unban") which works only on these ID's.

So if z.b. In the id.yml is "EinTollerName: 123" and then you enter "/ unban 321", you should get a message.

However, I do not know how to create the If query or how it should look like.

PS: Send that with the message, etc. I'll get it myself.

I assume now that you have the player name and the config file, etc. Already declared or initialized. The query would just be

if (cfg.getString (playername)) {
//
}

Hope that was what you meant:-)