How do I see how many milliseconds of ping a client has? I haven't tried anything yet because I don't have a clue what to do, if I search it online, I only get answers on how to ping in java, which is not what I need!
A ping / latency typically refers to the time it takes for an update packet to reach the destination (and back). So one way to determine the ping of a client from the server is to send some tiny packet from the client to the server with a field that looks something like this:
long sentMillis = System.currentTimeMillis();
which would contain the time in milliseconds when the packet was sent. Since you know when you got the packet on the server, capture current time in milliseconds:
long receivedMillis = System.currentTimeMillis();
// time from client to server long ping = receivedMillis - sentMillis;