Java

spackage sender;

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

public class Sender
{
	//declare a ServerSocket
	private static ServerSocket serverSocket;

	public static void main(String[] args)
	{
		System.out.println("Opening port...\n");

		try
		{
	       //create a ServerSocket with a port number 3000
		serverSocket = new ServerSocket(3000);
		}
		catch(IOException ioEx)
		{
		System.out.println("Unable to attach to port!");
		System.exit(1);
		}

		try
		{
               //create a new socket to connect with client and accept the connection 
		Socket link = serverSocket.accept();
		//create ObjectOutputStream that enable us to buffer array of bytes 
		ObjectOutputStream outStream = new   ObjectOutputStream(link.getOutputStream());
		//creat FileInputStream to obtain input bytes from a file
		FileInputStream fileIn = new FileInputStream("image.GIF");
		//get the file length
		long fileLen =  (new File("image.GIF")).length();
		//convert the length to int
		int intFileLen = (int)fileLen;
		//create an array of byte with the file length
		byte[] byteArray = new byte[intFileLen];
		//Read bytes of data from this input stream into an array of bytes
		fileIn.read(byteArray);
		//close this file input stream
		fileIn.close();
		//write the array of byte to the buffer (ObjectOutputStream)
		outStream.writeObject(byteArray);
		}
		catch(IOException e)
		{
		     System.out.println("error...");
		}
	}
}

package reciever;

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class Reciever
{
	public static void main(String[] args) throws Exception
	{

		try
		{
		//create a socket with the agreed port
		Socket link = new Socket("localhost",3000);
		//create ObjectOutputStream that enable us to buffer array of bytes 
		ObjectInputStream inStream = new ObjectInputStream(link.getInputStream());
		//create a array of bytes with the inputStream length (length of recieved array)
		byte[] byteArray = (byte[])inStream.readObject();
		//output stream for writing data to a File
	      	FileOutputStream outStream = new FileOutputStream("image.GIF");
	      	//Write byteArray to this file output stream
			                                                           outStream.write(byteArray);			
		//close the connection
		link.close();
		}
		catch(IOException e)
		{
			System.out.println("error...");
		}
	}
}

private boolean validateInput(String input1, String input2)
    {

        Boolean[] inputValidArray = {false , false};
        String[] inputArray = {input1, input2};

        JTextField[] textFieldArray = {jTextField1, jTextField2};

        float numberToValidate = 0;
        int counter = 0;   
        String errorMessage = "";

        while (!inputValidArray[0] || !inputValidArray[1])
        {
            try
            {
                // Check for empty or null input
                if (!(inputArray[counter].isEmpty() || inputArray[counter] == null))
                {
                    numberToValidate = Float.valueOf(inputArray[counter]);
                    inputValidArray[counter] = true;                
                }
                else
                {
                    errorMessage = "This field can not be left blank!\n" +
                                   "  Please enter a valid number!\n" +
                                   "  (example: 123.45 or -123.45)";

                    Create_Error_Message_Dialog_Box(errorMessage); 

                    textFieldArray[counter].requestFocusInWindow();
              
                }

            }
            catch (NumberFormatException nfe)
            {
                errorMessage = inputArray[counter] + " is not a valid number!\n" +
                               "Please enter a valid number!\n" +
                               "(example: 123.45 or -123.45)";

                Create_Error_Message_Dialog_Box(errorMessage);

                textFieldArray[counter].requestFocusInWindow();
                textFieldArray[counter].selectAll();

            }

            counter += 1;

        }
        
        return (inputValidArray[0] && inputValidArray[1]);
    }