How To Connect With Sockets From Other PCs

Dec 26, 2014

I have just started learning about sockets and such... and i have created a chat program with a server and a client

server:

public class Server {
private static ServerSocket server;
private static Socket connection;
private static PrintWriter pw;
private static BufferedReader br;
private static JTextField textOutput;

[Code] ....

so, everything is working fine . There is only one thing i would like to do now: make it so that i can run the server from my computer and then others can run the client from theirs and we will be able to chat . So I tried:

In the client code on line 56 is says:

connection = new Socket("localhost",7777);

So I changed "localhost",7777 to "myip",7777)

But when i run the server on my computer and run the client on another computer i get this error:

java.net.ConnectException: Connection refused: connect

Why is the connection getting refused? is it for security reasons? so hackers cant connect to me or something? And is there a way to tell your computer to allow that client to connect?

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Passing A Value For Sockets?

Mar 13, 2014

I am having a problem passing an int value from one class to the other. The gist of the objective of this program is to compute a local sum at each client, and then once the local sums are computed.. to compute the overall sum from all the clients. My problem is that I'm having trouble figuring out how to pass each sum from each individual client in the class multicastSenderReceiver to the readThread class. I keep getting an error.

I feel that I have to be able to pass the sum value from each client generated in multicastSenderReceiver to the other class, because that is the only way I'll accurately be able to sum up all the values..

Java Code:

package multicastsenderreceiver;
import java.net.*;
import java.io.*;
import java.util.*;
//import static multicastsenderreceiver.multicastSenderReceiver.numProcesses;
class multicastSenderReceiver{

[code]....

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I have all of my code written, but it is not producing any output and i'm not sure why.

import java.io.BufferedInputStream;
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import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;

[code]...

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Apr 11, 2014

Generally Socket Programming uses HTTP Protocol to send and receive messages in Java. Can we try to exchange HTTP/HTTPS requests instead of TCP?

a Socket constructs a HTTP request to send to another socket from information it has and sends to another one and Server responds with HTTPResponse.

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Aug 16, 2012

I created an instant messenger using java. When I have the Server that communicates between the clients and one client running on my Computer the CPU Usage is at 100%. It really slows down everything else I'm doing and I figure this might be an issue if I gave this to people to use. I don't want the client taking up a lot of CPU Usage if they're just running it in the background while doing other things on their computer. The program utilizes multithreading. Each thread is constantly being polled for input.

The Server, as seen below, has two threads. I explain what the threads do before the code. There is also another while loop running constantly in the server that is waiting for sockets to connect. The loop does not run constantly at the line socket.accept(); it stops and just waits.

The User, split into a menu and chat window, has two threads as well. I explain what the threads do before the code. After I originally posted I put a 100 ms sleep in all my threads. CPU Usage is still at 100%*

This thread listens for input from the user. The input tells the server what action to take. There is a thread running for every user currently connected to the server.

public void run()
{
try
{
input = new DataInputStream(user.getSocket().getInputStream());
output = new DataOutputStream(user.getSocket().getOutputStream());

[code]....

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Apr 8, 2014

I have written a java code to transfer files from one server to another using the concept of socket programming. I got the codes from another java forum that meet my requirements. The program is said to transfer large sized files (like .mkv , .mprg movies) from one machine to another and can be used to transfer files of all formats. But after running the codes I found that the program is not able to transfer large sized files such as movies and even pdf of sizes 80mb or 111mb. When i transfer small sized files, it gets transferred and the output shows that. You can run the codes and observe it. But when i try to transfer large sized files, the program goes on running for hours. The large sized files are not getting transferred. The program has used bytebuffer but still this error occurs.

**ClientMain.java**
import java.io.IOException;
import java.net.Socket;
public class ClientMain

[code]....

Note that:-

1. ClientMain.java and DirectoryTxr.java are the two classes under client application.
2. ServerMain.java and DirectoryRcr.java are the two classes under Server application.
3. run the ClientMain.java and ServerMain.java simultaneously

Also specify the source directory, destination directory and host address of the machine in which server is running in the ClientMain.java(as per your computer). Here we are not specifying source file ,instead a source directory or folder is specifying.So the entire files of source directory will be transferred.

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Dec 26, 2014

I have been practicing writing java code, my university course is going to cover socket programming and multi-threading.

I am presently just starting to write myself a framework for all multiplayer games I may make in the future, my aim really is simply to practice and understand better and this time, im not using an ide, just sublime text, all new grounds for me, I have a good basic understanding of the subject but I want to be fluent.

import java.net.*;
import java.util.ArrayList;
import java.io.*;
/*SMOOTH THREAD SAFE MULTI CLIENT HANDLING CLASS.
*
*This class will create connection objects when a connection is detected, these connections will run in a separate thread and update an array list in their parent class containing their last sent data

[Code] .....

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May 7, 2014

This question has confused me because "Errors" are capitalized and I'm not sure what they mean.

To me this question is false. Sockets can be used to transfers file over a network.

I can't see why this wouldn't work. The code looks fine to me.

I don't think this is true unless you're using the mouseEntered() or mouseExited() method. But again, I'm not sure.

I think this is true, I don't know what else could have listeners.

They're only worth a few marks each so the answer is only suppose to be a line or two. They are all true or false questions that require an explanation.

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Communicating Between Client And Server Sockets In Java

Apr 3, 2014

I'm working on an assignment right now which involves passing a variable series of numbers to the Server to be sorted into the correct order and returned to the client.

So far I have it connecting to the server and asking for my numbers, and I am entering each number and pressing return, and it is accepting each number individually.

One (smaller I think) problem i'm having is with the client code, specifically the while loop.. I've tried to code it so that when I enter a full stop ('.') the program will stop asking me for more numbers and move on to sending them to the server.. but instead it just crashes giving an error.. heres an example

"Enter a number: 1
Enter a number: 3
Enter a number: 2
Enter a number: 1.
java.lang.NumberFormatException: For input string: "1."
at java.lang.NumberFormatException.forInputString(Num berFormatException.java:65)

[Code] ....

Here's the client code in full

package numberSortprogram;
import java.io.*;
import java.net.ServerSocket;
public class NumSortClient {
public static void main(String[] args) {
InputStreamReader is = new InputStreamReader(System.in);
[Code] ....

The big problem that I have is figuring out how to send the sorted array back to the client..

So, what im trying to get to happen is-

-Client is asked to enter numbers
-Client enters series of numbers into an array
-Array is converted to a string and sent to the server
-String is then split into an array of strings and sorted using compareTo (don't know if this is the best way?)
-Sorted array is sent back to client and displayed.

fyi this is making use of streamsockets..

All of the rest of my code is below:

package numberSortprogram;
import java.io.IOException;
import java.net.*;
import java.util.regex.PatternSyntaxException;
public class NumSortServer {
public static void main(String[] args) {
int serverPort = 4444; // default port
if (args.length == 1 )

[Code] .....

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Basically I am looking for a similar concept as a message queue but more relevant to my requirements done in Java. What are some good options to use that will address some of my requirements? I have not touched Java in a long time and only have used it for certain usage so I am trying to get an idea of which current technologies are best for what I need.

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Server code:

Java Code:

public class Server extends JFrame {
//===============================
// FIELDS
//===============================
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[Code] ....

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import java.awt.*;
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[code]....

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[code]....

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[Code] ....

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package cs110.project3;
 import javafx.application.Application;
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[code].....

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&& (f[i][j+3] != " ")
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[code]....

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Java Code:

public class Connect

final static int MAXROW = 6;
final static int MAXCOL = 7;
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[code]....

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Apr 18, 2014

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. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .

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[Code] .....

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The answer to fixing my code is probably something small or something that will make me wonder why I hadn't thought of it myself... Here is my code:

import java.util.Scanner;
public class ConnectFour {
private static Scanner sc;
public static void main(String[] args)
{
sc = new Scanner(System.in);
System.out.print("Enter the height: ");
int h = sc.nextInt();
System.out.print("Enter the width: ");

[Code] .....

1 1 1 1
4 3 6 2
8 2 0 3
4 7 9 3

1 2 3 4
2 1 4 5
3 2 1 6
5 7 4 1

1 2 3 4
1 5 6 7
1 3 5 7
1 8 9 0

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For my job I would to develop a Java application which downloads some data from a webpage and then process them.

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[Code] .....
 
Sometimes it works fine, but usually I get the following exception:
 
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I don't understand what's the problem and why it's not persistent.

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