frist commit

src/ClientHandler.java

+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.net.Socket;
+
+public class ClientHandler {
+    private Socket socket;
+    private DataOutputStream dataOutputStream;
+    private DataInputStream dataInputStream;
+
+    public ClientHandler(Socket client) throws Exception {
+        if (client == null)
+            throw new Exception("client can't be null");
+        this.socket = client;
+        dataOutputStream = new DataOutputStream(client.getOutputStream());
+        dataInputStream = new DataInputStream(client.getInputStream());
+        run();
+    }
+    private void handleIncomingMessages(String message){
+        //TODO: implement this method
+    }
+    public void run() {
+        while(true){
+            try {
+                String input = dataInputStream.readUTF();
+                handleIncomingMessages(input);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}

src/Server.java

+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.ArrayList;
+
+public class Server {
+    private static final int PORT = 4321;
+    private ServerSocket serverSocket;
+    private ArrayList<String>user;
+    public Server() throws Exception {
+        serverSocket = new ServerSocket(PORT);
+        user=new ArrayList<>();
+
+        while (true) {
+            Socket client = serverSocket.accept();
+            ClientHandler clientHandler = new ClientHandler(client);
+        }
+    }
+}
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