Simple Calculator using Java Socket Programming

Prerequisite: Socket Programming in Java

First, we understand the basics of java socket programming. Java Socket is used to communicate between two different JREs. Java socket can be connection-oriented or connection-less. In java, we have a package called “java.net”. In this package, we have two classes Socket Class and Server Class. Those classes are used to create connection-oriented or connection-less programs. In this article, We will see how the java server will perform the basic operations and send back the result to the java client 

Java Client

First, we create and write client-side socket code. In client socket program must know two information

• IP Address of Server and,
• Port Number

Java

// A Java program for a Client
import java.io.*;
import java.net.*;
import java.util.*;

public class Client {
    private Socket s = null;
    public Client(String address, int port)
    {
        try {
            // In this Code Input Getting from a user
            Scanner sc = new Scanner(System.in);
            s = new Socket(address, port);
            System.out.println("Connected");

            // Create two objects first is dis and dos for
            // input and output
            DataInputStream dis
                = new DataInputStream(s.getInputStream());
            DataOutputStream dos
                = new DataOutputStream(s.getOutputStream());

            // Making a Loop
            while (true) {
                System.out.println(
                    "Enter the operation in the form operand operator operand");
                System.out.println("Example 3 + 5 ");
                String inp = sc.nextLine();

                // Check the user input if user enter over
                // then
                // connect is stopped by server and user
                if (inp.equals("Over"))
                    break;
                dos.writeUTF(inp);

                String ans = dis.readUTF();
                System.out.println("Answer = " + ans);
            }
        }
        catch (Exception e) {
            System.out.println("Error in Connection");
        }
    }

    public static void main(String args[])
    {
        // Connection With Server port 5000
        Client client = new Client("127.0.0.1", 5000);
    }
}

Java Server

In this Java Server, we are performing simple calculations example addition, subtraction, etc. In this Code first, we receive input from the client-side. We pass this information to the “Stringtokenizer class” this class help to extract the exact “operand and operation” to perform the operation. when the result is ready java server sends it back to the result client

Java

// A Java program for a Server
import java.io.*;
import java.net.*;
import java.util.*;

public class Server {
    // initialize socket and input stream
    private Socket socket = null;

    // constructor with port
    public Server(int port)
    {
        try {
            // Making a ServerSocket  object
            // for receiving Client Request
            ServerSocket ss = new ServerSocket(port);
            Socket s = ss.accept();

            // dis and dos object for receiving
            // input from client send output to client
            DataInputStream dis
                = new DataInputStream(s.getInputStream());
            DataOutputStream dos
                = new DataOutputStream(s.getOutputStream());

            while (true) {
                String input = dis.readUTF();
                if (input.equals("bye"))
                    break;
                System.out.println("Equation Received");
                int result = 0;

                StringTokenizer st
                    = new StringTokenizer(input);
                int oprnd1
                    = Integer.parseInt(st.nextToken());
                String operation = st.nextToken();
                int oprnd2
                    = Integer.parseInt(st.nextToken());

                // Calculator Operation Perform By Server
                if (operation.equals("+")) {
                    result = oprnd1 + oprnd2;
                }
                else if (operation.equals("-")) {
                    result = oprnd1 - oprnd2;
                }
                else if (operation.equals("/")) {
                    result = oprnd1 / oprnd2;
                }
                else if (operation.equals("*")) {
                    result = oprnd1 * oprnd2;
                }
                System.out.println("Sending the Result");
                dos.writeUTF(Integer.toString(result));
            }
        }
        catch (Exception e) {
            System.out.println("Error");
        }
    }

    public static void main(String args[])
    {
        // Server Object and set port number 5000
        Server server = new Server(5000);
    }
}

Output: