How to Create a simple TCP Client-Server Connection in Java?

TCP can be defined as Transmission Control Protocol. This is the standard protocol for transmitting data over a network. It provides reliable, structured, and error-checked data delivery between applications running on hosts connected via an IP (Internet Protocol) network. In Java, we can create TCP client-server connections using the Socket and ServerSocket classes from the java.net package .

In this article, we will learn how to create a simple TCP client-server connection in Java.

TCP client-server connection

TCP client-server communication consists of two important components. These two consist of a server and more than one client.
The servers receive incoming connections from clients on a specific port number using a ServerSocket.
The client then connects to the port using a Socket with the server’s IP address.
Once the connection is created, the data can be exchanged between the server and the client using input and output streams .

Key Terminologies

TCP : Transmission Control Protocol used to transmit data over a network and can provide network communications, point-to-point communication channels and can ensure data integrity and sequencing.
Socket : It is the terminal connection between two devices on the network and the Socket class can represent the client-side socket and can provide a connection to the server

Step-by-Step implementation of Server-Side to Create Connection

Create the Java class named Server in that class write the main method.
Create the instance of the ServerSocket and assign the port as 9090.
Accept the client connections using accept() method of the ServerSocket to the wait for incoming client connections.
Now, we can setup the input and output streams of the client socket and read and process the client data.
Send the response to the client and close the sockets.

Implementation:

Output:

Before client connected to the server:

Server is running and waiting for client connection.

After client connected:

Server side Output

Step-by-Step implementation of Client-Side to Create Connection

Create the Java class named as Client in that class write the main method of the program.
Create the instance of the Socket and assign the port as 9090.
Setup the input and output streams and send the data to the server.
Setup the receive the response from the server.
Close the socket.

Implementation:

Output:

Below we can see the output received by the client in console.

Client side Output

In the above example, we have created a TCP connection between client and server by sending and receiving data between client and server on port 9090.