Connecting with computers outside the local network in Java

Question

I found some basic examples online about sending messages between computers in Java. However i realized that i only used local ip addresses so i could only send messages to a pc connected in the same network. I rewrote most of the code to make a slightly better version but if i wanted to send a message to a computer in a different network, connected to the internet, would switching the local ip with the receiving computer's public ip address in the code do the trick?

Answer 1

简短回答： 是的 ，只要接收方计算机具有公共地址且没有代理阻止请求。

Answer 2

Yes it should work, however it's common place to connect to the Internet via a modem, which in term is the device holding the public IP. Some NAT and likely port forwarding would be needed at the endpoint.