This is my client, server and server-request handler can you please give me hint how I will send a packet and ACK?

Client

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class Client {

	public static void main(String args[]) {

		try {
			Socket client = new Socket("localhost", 2983);
			ObjectInputStream ois;
			ObjectOutputStream oos;
			Scanner input = new Scanner(System.in);
			
			while (true) {
				// receving
				ois = new ObjectInputStream(client.getInputStream());
				String msg = ois.readUTF();
				System.out.println(msg);
				
				// sending
				oos = new ObjectOutputStream(client.getOutputStream());
				String message;
				System.out.print("Client:");
				message = input.nextLine();
				oos.writeUTF("Client:" + message);
				oos.flush();
			}
		} catch (Exception ex) {
			System.out.println(ex);
		}
	}

}

RequestHandler

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class RequestHandler extends Thread{

	Scanner input = new Scanner(System.in);
	Socket client_acp;
	ObjectInputStream ois;
	ObjectOutputStream oos;
	String message;
	public RequestHandler(Socket client){
		client_acp = client;
	}
	
	@Override
	public void run() {
		
		try {
			while (true) {
				//sending
				oos = new ObjectOutputStream(client_acp.getOutputStream());
				System.out.print("Server:");
				message = input.nextLine();
				oos.writeUTF("Server:" + message);
				oos.flush();
				
				// receving
				ois = new ObjectInputStream(client_acp.getInputStream());
				String msg = ois.readUTF();
				System.out.println(msg);
				
			}
		} catch (Exception e) {
			System.out.println(e);
		}
	}
}

Server

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class Server {

	public static void main(String args[]) {
		try {
			ServerSocket server_socket = new ServerSocket(2983);
			System.out.println("Waiting for client request");

			while (true) {
				Socket client = server_socket.accept();
				System.out.println("Accepted connection request");
				RequestHandler obj = new RequestHandler(client);
				obj.start();
			}
		} catch (Exception e) {
			System.out.println(e);
		}

		// Scanner input = new Scanner(System.in);
	}
}