This is probably the most basic example you can get:
```
import java.io.BufferedOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.nio.ByteBuffer;
public class Main {
public static void main(String[] args) throws Exception {
Socket socket = new Socket("localhost", 9998);
String command = "0006303030304e43";
// the following line converts the hex command string to a byte array
byte[] bytes = ByteBuffer.allocate(8).putLong(Long.parseLong(command, 16)).array();
OutputStream out = socket.getOutputStream();
BufferedOutputStream bufferedOut = new BufferedOutputStream(out, 1024);
bufferedOut.write(bytes);
bufferedOut.flush();
InputStream in = socket.getInputStream();
int result;
while ((result = in.read()) != -1) {
System.out.print((char)result);
}
socket.close();
}
}
```
To understand the meaning of the string ```0006303030304e43```, it can be broken down as follows (in reverse order):
- ```4e43``` is the 2 byte command ```NC``` as hex
- ```30303030``` adds a 4 byte header ```0000``` as hex
- ```0006``` represents the length in hex of the comamnd and header (i.e. the length of ```0000NC```)