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the buffer in server doesn't read the value that client sent

The client sends data (string) to the server, and the server must read it, but in my case the server didn't read the data (value) that the client sent, and I didn't know where is the problem exactly, because normally the steps to read data are all correct in the server side
Client side:
Socket socket = new Socket(address, authenticationServerPort);
username = username + "\n"; // to send username through socket without
String h=getUserInput();
// waiting
// Send the message to the server
// send public key
OutputStream os = socket.getOutputStream();
OutputStreamWriter osw = new OutputStreamWriter(os);
BufferedWriter bw = new BufferedWriter(osw);
System.out.println(h);
bw.write(h);
bw.flush();
System.out.println("Message sent to the Authentication server : "+ h);
Server side:
Socket clientSocket = null;
try {
System.out.println("Server Running");
int serverPort = 8029; // the server port we are using
ServerSocket listenSocket = new ServerSocket(serverPort);
List<BlockChain> resultList = new ArrayList<BlockChain>();
while (true) {
clientSocket = listenSocket.accept();
InputStream is = clientSocket.getInputStream();
System.out.println(is);
InputStreamReader isr = new InputStreamReader(is);
System.out.println(isr);
BufferedReader br = new BufferedReader(isr);
String request = br.readLine();
System.out.println("the msg receving from client is : "+request);
PrintWriter out;
out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream())));
if (clientSocket != null) {
clientSocket.close();
}
}
catch (Exception e) {
e.printStackTrace();// TODO: handle exception
}
}
Someone tell me where is the problem exactly.

Connecting raspberry to java serverSocket

I am trying to make raspberry listen to the java socket server. I run the server code with eclipse and then log in to raspberry desktop and run client.jar. When i run client.jar it does not connect to my server and does not throw any errors. It just 'stays' in the Lxterminal forever and does nothing.
Server
int port = 6666;
Inet4Address add = (Inet4Address) Inet4Address.getLocalHost();
System.err.println(add);
ServerSocket server = new ServerSocket(6666, 1, add);
Socket client = server.accept();
System.err.println("acc");
DataInputStream in = new DataInputStream(client.getInputStream());
DataOutputStream out = new DataOutputStream(client.getOutputStream());
while (true){
BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
String line = read.readLine();
out.writeUTF(line);
out.flush();
System.err.println(in.readUTF());
}
Client
int port = 6666;
Socket server = new Socket("My ip", port);
DataInputStream in = new DataInputStream(server.getInputStream());
DataOutputStream out = new DataOutputStream(server.getOutputStream());
while (true)
{
String msg = in.readUTF();
if (msg.contentEquals("close"))
server.close();
else if (msg.equals("forward"))
{
out.writeUTF("I go forward master");
out.flush();
}
UPDATE:
I have resolved this problem few seconds ago.My firewall was blocking any connection so the raspberry couldn't connect.
Solution: Go to firewall and network connection and turn it off for private and public connections. I am using Win10

Android java How to connect to server with different network/ip address

How to connect to server with different IP address
I really don't know what to do...
Let me explain first.
i have a client and server that works great when sending messages between the two if i am on the same network as my computer.
i have an android device and i would like to wish when ever i am placed far away and when i will click some button it will send message to server even if i am not on the same network.
Client
try {
client = new Socket("IpAddress", 4444);
BufferedReader in = new BufferedReader(
new InputStreamReader(client.getInputStream()));
printlng = new PrintWriter(client.getOutputStream());
printlng.println(mlng);
printlng.flush();
while (true) {
if ((Response= in.readLine()) != null) {
Log.i("Response:", Response);
dlng = Double.valueOf(Response);
System.out.println(dlng);
break;
}
}
Server:
public static void main(String[] args) {
try {
serverSocket = new ServerSocket(4444); // Server socket
} catch (IOException e) {
System.out.println("Could not listen on port: 4444");
}
System.out.println("Server started. Listening to the port 4444");
while (true) {
try {
clientSocket = serverSocket.accept(); // accept the client
inputStreamReader = new InputStreamReader(
clientSocket.getInputStream());
bufferedReader = new BufferedReader(inputStreamReader); // get
// the
// client
PrintWriter out = new PrintWriter(
clientSocket.getOutputStream(), true);
InputStream inputStream = new ByteArrayInputStream(
bufferedReader.readLine().getBytes(
Charset.forName("UTF-8")));
BufferedReader bufferedReader2 = new BufferedReader(
new InputStreamReader(inputStream));
String output = bufferedReader2.readLine();
System.out.println(output.toString());
out.println(output.toString());
out.flush();
out.close();
inputStreamReader.close();
clientSocket.close();
} catch (IOException ex) {
System.out.println("Problem in message reading");
}
}
}

You have to find out the external/internet ip address of the pc where your server is running on. You can do that on that pc with http://whatismyip.com. Use the obtained ip in your client. But before it really can work you have to configure the router where your pc is connected to to forward the used port to the lan ip address of your pc.

If everything works fine when you are on the same LAN : the problem is probably coming from some firewall rule not accepting connection on port 4444 when coming from a non local IP.
So, either change the port of the server (if not used yet, port 80 is probably a good choice since there is more chance that connections will be allowed), either change your firewall rules.

client/server to send a file get stuck somewhere

I have implemented a client/server to send files . When there is no more messages exchanged after sending the file , the code works perfectly , but if the client sends some string to the server directly after the code of receiving the file both client and server stop doing anything and the file is not sent it's something like if they both get stuck in deadlock but I'm not really sure :
Here is the code to send the file without sending anything after it , which works:
Client
String filename;
BufferedReader UIn = new BufferedReader(new InputStreamReader(System.in));
Socket peer = new Socket("localhost",9999);
System.out.print("Enter the file name to download :");
filename= UIn.readLine();
///////////////////////////////
DataOutputStream OutToServer;
OutToServer = new DataOutputStream(peer.getOutputStream());
OutToServer.writeBytes(filename+"\n");
FileOutputStream fos = new FileOutputStream(new File("D:/new.txt"));
BufferedOutputStream out = new BufferedOutputStream(fos);
InputStream in = peer.getInputStream();
buffer = new byte[1024];
while((count=in.read(buffer))>0)
{
fos.write(buffer, 0, count);
System.out.println(buffer);
}
fos.close();
System.out.println("done");
Server:
ServerSocket server =null;
try {
server = new ServerSocket(9999);
while(true)
{
client= server.accept();
//System.out.println("Connection accepted");
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(client.getInputStream()));
DataOutputStream outToclient =new DataOutputStream(client.getOutputStream());
String request=inFromClient.readLine();
file = new File(request);
if (file.exists())
{
OutputStream out = client.getOutputStream();
BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
while((count =in.read(buffer)) >0)
{
out.write(buffer,0,count);
out.flush();
}
}
// System.out.println(request);
// outToclient.writeBytes("alaa\n");
}
} catch (IOException ex) {
Logger.getLogger(ServerWork.class.getName()).log(Level.SEVERE, null, ex);
}
But if I try to send anything after the loop between client and server it stops working . Is it because I'm using readLine() and writeBytes()?

You are using both DataOutputStream and OutputStream. I think that they
should work together but what I guess you should do is to flush the buffer (or close it).
After you're done writing everything you want to send, some data may still be in the buffer. Now you will have to flush the buffer, to force it to send all the data.(as it is said here).
outToclient.writeBytes("alaa\n");
outToclient.flush();

Send string to client upon command JAVA

So I am trying to have a sever sit and listen waiting for a connection from a client. The client sends over some string and the sever does some action based on whats received. Now what I would like to happen is the client sends over some command asking for data back and have the server get what it needs to and send the string back.
Not a big deal right? Well for some reason I can't get it working, my best guess is that its not closing the socket properly. I can't figure out why it wouldn't or what I am doing wrong.
Client
String data = "";
DataOutputStream outToServer = null;
BufferedReader input;
try {
outToServer = new DataOutputStream(clientSocket.getOutputStream());
outToServer.writeBytes("GETDATA");
outToServer.flush();
input = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
data = input.readLine();
Log.d("ANSWER: ", data);
input.close();
} catch (IOException e) {
Log.d("Error: ", e.toString());
}
Server
ServerSocket listeningSocket = new ServerSocket(9008);
BufferedReader fromClient ;
PrintStream os;
while(true) {
Socket clientSocket = listeningSocket.accept();
ServerConnection clientConnection = new ServerConnection(clientSocket);
os = new PrintStream(clientSocket.getOutputStream());
fromClient= new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
if(fromClient.readLine().equals("GETDATA")){
os.println("DATA");
os.flush();
clientSocket.wait();
clientSocket.close();
}
else{
clientConnection.run();
}
}
Any ideas?

here is your error
outToServer.writeBytes("GETDATA");
the right code is
outToServer.writeBytes("GETDATA\n");
as your using readline you should send a full line with line break