Client0.java

package com.n1nja.networking;
import java.io.*;
import java.net.*;
import java.util.Arrays;
public abstract class Client {
	private final Socket socket;
	private BufferedReader netReader;
	private BufferedWriter netWriter;
	public Client() {
		socket = new Socket();
	}
	public Client(InetAddress hostAddress, int port) {
		this();
		this.connect(hostAddress, port);
	}
	public void connect(InetAddress hostAddress, int port) {
		try {
			this.socket.connect(new InetSocketAddress(hostAddress, port));
			this.netReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
			this.netWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public boolean isConnected() {
		return this.socket.isConnected();
	}
	public void start() {
		new Thread(
			new Runnable() {
				@Override
				public void run() {
					BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
					while (true) {
						try {
							if (consoleReader.ready()) {
								String[] args = consoleReader.readLine().split(" ");
								command(args[0].toUpperCase(), Arrays.copyOfRange(args, 0, args.length));
							}
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
				}
			}
		).start();
	}
	public void stop() {
		if (!this.socket.isClosed()) {
			try {
				this.socket.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		System.exit(0);
	}
	public void write(char c) {
		this.write((int) c);
	}
	public void write(int i) {
		try {
			this.netWriter.write(i);
			this.netWriter.flush();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public void writeLine(String s) {
		try {
			this.netWriter.write(s + System.getProperty("line.separator"));
			this.netWriter.flush();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public int read() {
		int read = -1;
		try {
			read = this.netReader.read();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return read;
	}
	public String readLine() {
		String readLine = null;
		try {
			readLine = this.netReader.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return readLine;
	}
	public abstract void command(String command, String[] params);
}

Client1.java

package com.limyc.limychat.client;
import java.net.*;
import com.limyc.chat.CHAT;
import com.limyc.limychat.User;
public class Client extends com.n1nja.networking.Client {
	private static enum Command {
		CONNECT(new String[] {
			"CONNECT"
		}),
		STOP(new String[] {
			"STOP",
			"EXIT",
			"QUIT"
		});
		private String[] aliases;
		private Command(String[] aliases) {
			this.aliases = aliases;
		}
		public String toString() {
			return aliases[0];
		}
		public boolean matches(String s) {
			boolean matches = false;
			matcher:for (String a : aliases) {
				if (a.equalsIgnoreCase(s)) {
					matches = true;
					break matcher;
				}
			}
			return matches;
		}
	}
	public static void main(String[] args) {
		new Client().start();
	}
	private User user;
	private boolean isRegistered;
	public Client() {
		super();
		this.user = null;
		this.isRegistered = false;
	}
	@Override
	public void start() {
		super.start();
		System.out.println("Type \"connect <IP:port>\" to connect to a server.");
	}
	@Override
	public void stop() {
		this.disconnect();
		super.stop();
	}
	@Override
	public void command(String command, String[] params) {
		if (Command.CONNECT.matches(command) && params.length >= 1) {
			String[] address = params[0].split(":");
			try {
				this.connect(InetAddress.getByName(address[0]), Integer.parseInt(address[1]));
			} catch (NumberFormatException | UnknownHostException e) {
				e.printStackTrace();
			}
		} else if (Command.STOP.matches(command) && params.length >= 0) {
			this.stop();
		}
	}
	public void register(String name) {
		User register = null;
		if (this.isConnected()) {
			this.writeLine(CHAT.getCommand(CHAT.Command.REGISTER) + ":" + name);
			String response = null;
			do {
				response = this.readLine();
			} while (response == null);
			if (response.split(":")[2].equals(CHAT.Code.REGISTER_SUCCESS.toString())) {
				register = new User(name, response.split(":")[3]);
				this.isRegistered = true;
			}
		} else {
			System.out.println("Not connected. Type \"connect <IP:port>\".");
		}
		this.user = register;
	}
	public void message(String message) {
		if (this.isRegistered) {
			this.writeLine(CHAT.getCommand(CHAT.Command.MESSAGE) + ":" + this.user.getID() + ":" + message);
		} else {
			System.out.println("Not registered. Type \"register <name>\".");
		}
	}
	public void disconnect() {
		if (this.isConnected()) {
			this.writeLine(CHAT.getCommand(CHAT.Command.DISCONNECT));
		}
	}
}