The aim is to transfer the coordinates from one Client(who is drawing) to all the Clients Connected to the Server and then draw on their respective Panels, but the readObject() in Client never seems to fetch the data. The Input Does go to the Server Properly but from Server, the Other CLients Couldn't Listen to it.
When using BufferedStream or DataInput/OutputStream any Other the input seems to lag or misbehaving. So preferring ObjectOutputStream. Snapshot of the Program.
The Client listens for the input in a background Thread listenData.
The Client Code -
public class Clients extends JFrame {
private static final long serialVersionUID = 1L;
private Coordinates crdntsToSend;
private Coordinates crdntsReceived;
private JPanel contentPane;
private Socket socket;
private ObjectOutputStream toServerPipe;
private ObjectInputStream fromServerPipe;
private JPanel paintPanel;
public Clients(String name,int port,String ip) {
setResizable(false);
setTitle("Skribbl");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(600,550);
createConnection(ip,port);
listen();
}
private void createConnection(String ip,int port)
{
try {
socket = new Socket(ip,port);
toServerPipe = new ObjectOutputStream(socket.getOutputStream());
fromServerPipe = new ObjectInputStream(socket.getInputStream());
toServerPipe.flush();
userInterfaceSetter();
} catch (IOException e) {
System.out.println("Port Not Found!!!");
return;
}
}
private void userInterfaceSetter()
{
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e1) {
e1.printStackTrace();
}
getContentPane().setLayout(null);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
gbl_contentPane.columnWidths = new int[] {0, 0};
gbl_contentPane.rowHeights = new int[]{0, 0, 0};
gbl_contentPane.columnWeights = new double[]{1.0, Double.MIN_VALUE};
gbl_contentPane.rowWeights = new double[]{1.0, 0.0, Double.MIN_VALUE};
contentPane.setLayout(gbl_contentPane);
paintPanel = new JPanel();
paintPanel.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
drawOnPanel(e.getX(),e.getY());
}
});
paintPanel.addMouseMotionListener(new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent e) {
drawOnPanel(e.getX(),e.getY());
}
});
paintPanel.setBackground(new Color(175, 238, 238));
GridBagConstraints gbcPaintPanel = new GridBagConstraints();
gbcPaintPanel.insets = new Insets(10, 10, 10, 10);
gbcPaintPanel.fill = GridBagConstraints.BOTH;
gbcPaintPanel.gridx = 0;
gbcPaintPanel.gridy = 0;
contentPane.add(paintPanel, gbcPaintPanel);
JLabel lblScore = new JLabel("Score: ");
GridBagConstraints gbclblScore = new GridBagConstraints();
gbclblScore.insets = new Insets(0, 0, 10, 0);
gbclblScore.anchor = GridBagConstraints.WEST;
gbclblScore.gridx = 0;
gbclblScore.gridy = 1;
contentPane.add(lblScore, gbclblScore);
}
private void drawOnPanel(int x,int y)
{
Graphics g = paintPanel.getGraphics();
g.fillOval(x, y, 7, 7);
sendData(x,y);
}
private void sendData(int x, int y) {
try {
crdntsToSend = new Coordinates(x,y);
toServerPipe.writeObject(crdntsToSend);
toServerPipe.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
private void listen()
{
SwingWorker<Void, String> listenData = new SwingWorker<Void, String>() {
boolean go = true;
String[] receivedData;
String str;
@Override
protected Void doInBackground() throws Exception {
while(go)
{
crdntsReceived = (Coordinates) fromServerPipe.readObject();
str= crdntsReceived.toString();
publish(str);
}
return null;
}
@Override
protected void process(List<String> chunks) {
receivedData = str.split(" ");
drawOnPanel(Integer.parseInt(receivedData[0]),Integer.parseInt(receivedData[1]));
}
};
listenData.execute();
}
}
ServerHandler Code(Server Thread) -
package theskribbl;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
public class HandleClient implements Runnable
{
private Socket[] socket;
private ObjectInputStream fromClients;
private ObjectOutputStream toClients;
private static int count = 0;
private int temp;
public HandleClient(Socket[] socket, int count)
{
HandleClient.count = count;
temp=count;
this.socket=socket;
try
{
fromClients = new ObjectInputStream(socket[count].getInputStream());
toClients = new ObjectOutputStream(socket[count].getOutputStream());
toClients.flush();
}
catch (IOException e)
{
e.printStackTrace();
}
}
@Override
public void run()
{
int i;
Coordinates coordinate;
while(true)
{
i=0;
try
{
coordinate = (Coordinates) fromClients.readObject();
System.out.println(coordinate.toString());
while(i<=count)
{
if(i!=temp)
{
toClients = new ObjectOutputStream(socket[i].getOutputStream());
toClients.writeObject(coordinate);
toClients.flush();
}
i++;
}
}
catch (Exception e)
{
System.out.println("Something Went Wrong");
return;
}
}
}
}
code of Client - https://repl.it/@GirirajSingh/skribbl#Clients.java
code for Logging into Client - https://repl.it/@GirirajSingh/skribbl#Login.java
code for Handling the Client(Server Side) - https://repl.it/@GirirajSingh/skribbl#HandleClient.java
code of Server - https://repl.it/@GirirajSingh/skribbl#ServerClass.java
question from:
https://stackoverflow.com/questions/65875017/the-readobject-method-of-objectoutputstream-is-not-receiving-the-object-writte 
