Java Tutorial : How To Create Connection With Socket Programming On...

Repository

https://github.com/dmlloyd/openjdk

What Will I Learn?

You will learn how to create connection with socket programming
You will learn connect two program in one package
You will learn how to create method like chatting Apps

Requirements

you must know basic of java programming
you must know about socket programming
you must know how to set port on two program

Difficulty

Intermediate

Tutorial Contents

okay, on this occasion I will create a tutorial on how to create a connection using socket programming, socket programming is very widely used in large applications such as chat application or application sender file . and this time I will make the method.

the first step you should do is create a new package in NetBeans.

then name it for the package you have created

then create a new class by name server.java

then type the program below, I will explain it.

package socketprogramming;
import java.io.*;
import java.net.*;
public class server{
    ServerSocket providerSocket;
    Socket connection = null;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;
    server(){}
    void run()
    {
        try{
            providerSocket = new ServerSocket(2004, 10);
            System.out.println("Waiting for connection");
            connection = providerSocket.accept();
            System.out.println("Connection with IP " + connection.getInetAddress().getHostName());
            out = new ObjectOutputStream(connection.getOutputStream());
            out.flush();
            in = new ObjectInputStream(connection.getInputStream());
            sendMessage("Program is successful Connected");           
            do{
                try{
                    message = (String)in.readObject();
                    System.out.println("client>" + message);
                    if (message.equals("hi....!"))
                        sendMessage("Hi... to");
                }
                catch(ClassNotFoundException classnot){
                    System.err.println("Data received ");
                }
            }while(!message.equals("bye"));
        }
        catch(IOException ioException){
      }
        finally{
            try{
                in.close();
                out.close();
                providerSocket.close();
            }
            catch(IOException ioException){
            }
        }
    }
    void sendMessage(String msg)
    {
        try{
            out.writeObject(msg);
            out.flush();
            System.out.println("server>" + msg);
        }
        catch(IOException ioException){
        }
    }
    public static void main(String args[])
    {
        server server = new server();
        while(true){
            server.run();
        }
    }
}

okay, I'll explain the important parts of the above program:
package socketprogramming; this is the declaration of the package name, make sure you create both programs in the same package.
import java.io. *; this is a class that works for input and output process.
below is the process of creating object socket programming that we will call in the program.

ServerSocket providerSocket;
Socket connection = null;

this is the declaration of the input object, output, and to display the message.

ObjectOutputStream out;
ObjectInputStream in;
String message;

server () This is a class declaration server.
this is the process of calling the object we have created before.

providerSocket = new ServerSocket(2004, 10);
System.out.println("Waiting for connection");

connection = providerSocket.accept();this is the process of receiving connections.
This works to show that the system has been successfully connected with the IP address that has been determined.

System.out.println("Connection with IP " + connection.getInetAddress().getHostName());

below serves to display the input, output and connection

out = new ObjectOutputStream(connection.getOutputStream());
            out.flush();
            in = new ObjectInputStream(connection.getInputStream());
            sendMessage("Program is successful Connected");

this is the conditioning of the situation that occurs when the program is run.

do{
                try{
                    message = (String)in.readObject();
                    System.out.println("client>" + message);
                    if (message.equals("hi....!"))
                        sendMessage("Hi... to"); }
                catch(ClassNotFoundException classnot){
                    System.err.println("Data received ");
                }}while(!message.equals("bye"));
        }catch(IOException ioException){
      }

this is to close the programming socket.

in.close();
                out.close();
                providerSocket.close();

okay, I think it's enough explanation for the server program, then we will create a class client

type the program below for the class client

package socketprogramming;
import java.io.*;
import java.net.*;
public class client{
    Socket requestSocket;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;
    client(){}
    void run()
    {
        try{requestSocket = new Socket("localhost", 1718);
            System.out.println("Connected to localhost in port 1718");
            out = new ObjectOutputStream(requestSocket.getOutputStream());
            out.flush();
            in = new ObjectInputStream(requestSocket.getInputStream());
            do{
                try{
                    message = (String)in.readObject();
                    System.out.println("server>" + message);
                    sendMessage("Hi my server");
                    message = "bye";
                    sendMessage(message);
                }
                catch(ClassNotFoundException classNot){
                    System.err.println("data received in unknown format");
                }
            }while(!message.equals("bye"));
        }
        catch(UnknownHostException unknownHost){
            System.err.println("You are trying to connect to an unknown host!");
        }
        catch(IOException ioException){ }
        finally{
            try{in.close();
                out.close();
                requestSocket.close();
            }
            catch(IOException ioException){
            }}}
    void sendMessage(String msg)
    {try{
            out.writeObject(msg);
            out.flush();
            System.out.println("client>" + msg);}
        catch(IOException ioException){
        }}public static void main(String args[])
    {   client client = new client();
        client.run();
    }}

I do not think much need to explain again to the second program because basically almost the same, but only different in some part only.

Socket requestSocket; this is for connection request
try {requestSocket = new Socket (" localhost ", 1718); and this is for connection creation
System.out.println (" Connected to localhost in port 1718 "); This is for notification that the program is successfully connected.
okay, both programs we have created, then we will try to run the program if it will successfully connected.
we just to right click on the server program and select run file.