客户端未连接到服务器

Question

I decided to rewrite my client, but it's not letting me connect to my server. My old client still connects, so I'm not really sure what I'm doing wrong.

My friend wrote most of the old client, I just did the socket work on it, and it worked.

In my Stream.java class, the System.out.println("Connecting"); shows in my connectToServer(); method, but the System.out.println(isConnected); does not trigger.

NOTE: I'm most likely gonna switch to CardLayout for my panels, I'm just testing different stuff. Please only post about the issue itself.

This is what I have:

Client.java

package Main;

import java.net.Socket;

import Frame.ClientFrame;
import Stream.FilteredStream;
import Stream.Stream;

public class Client implements Runnable {
    public static boolean loggedIn = false;
    public static Stream stream;

    Socket clientSocket;

    ClientFrame frame;
    Thread clientThread;

    public synchronized void start() {
        clientThread = new Thread(this);
        clientThread.start();
    }
    public synchronized void stop() {
        clientThread.interrupt();
    }
    public void run() {
        stream = new Stream(clientSocket);
        frame = new ClientFrame("Login");
        frame.displayFrame();

        while(loggedIn){

        }

    }

    public static void main(String[] args) {
        new Client().start();
    }
}

ClientFrame.java:

package Frame;

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

import Main.Client;

public class ClientFrame extends JFrame implements ActionListener {
    String name;

    public ClientFrame(String name) {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.name = name;
    }

    private JButton loginButton;
    private JButton newAccButton;
    private JTextField usertextfield;
    private JTextField passtextfield;
    private JLabel label;


    public JPanel mainpanel;
    JPanel infopanel;

    public void disposePanel(String name) {
        switch(name) {
        case "mainpanel":
            mainpanel.removeAll();
        }
    }


    public void displayFrame() {
        switch(name) {
        case "Login": 
            int panelStage = 0;
            setSize(300, 150);

            mainpanel = new JPanel();
            mainpanel.setLayout(new GridBagLayout());
            GridBagConstraints c = new GridBagConstraints();

            JLabel connect = new JLabel("Connecting to Server...");
            connect.setFont(new Font("Felix Titling", Font.BOLD, 24));
            mainpanel.add(connect, c);

            while(!Client.stream.isConnected) {
                if(panelStage < 1) {
                    add(mainpanel);
                    setVisible(true);
                    panelStage++;
                }
                try{
                    Client.stream.connectToServer();
                }catch(IOException e) { e.printStackTrace(); }
            }
            disposePanel("mainpanel");

            mainpanel.setLayout(new BorderLayout());

            infopanel = new JPanel();
                label = new JLabel("Username: ");
                infopanel.add(label, BorderLayout.WEST);

                usertextfield = new JTextField("Username", 10);
                usertextfield.addActionListener(this);
                usertextfield.setText("");
                infopanel.add(usertextfield, BorderLayout.EAST);
            mainpanel.add(infopanel, BorderLayout.NORTH);

            infopanel = new JPanel();
                label = new JLabel("Password: ");
                infopanel.add(label, BorderLayout.WEST);

                passtextfield = new JTextField("Password", 10);
                passtextfield.addActionListener(this);
                passtextfield.setText("");
                infopanel.add(passtextfield, BorderLayout.EAST);
            mainpanel.add(infopanel, BorderLayout.SOUTH);

            infopanel = new JPanel();
                loginButton = new JButton("Login");
                loginButton.addActionListener(this);
                infopanel.add(loginButton, BorderLayout.WEST);

                newAccButton = new JButton("New Acc");
                infopanel.add(newAccButton, BorderLayout.EAST);

            mainpanel.add(infopanel, BorderLayout.SOUTH);

            add(mainpanel);
            setResizable(false);
            setVisible(true);
            break;
        case "Chat":
            break;
        }
    }

    String loginUsername;
    String loginPassword;

    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == loginButton){
            if(usertextfield.getText().length() > 0) {
                if(passtextfield.getText().length() > 0) {
                    loginUsername = usertextfield.getText();
                    loginPassword = passtextfield.getText();
                }
            }
            try {
                Client.stream.sendData("LOGININFO"+" "+loginUsername+" "+loginPassword);
            }catch(IOException exception) { exception.printStackTrace(); }
        }
        if(e.getSource() == userText) {
            if(userText.getText().length() > 0) {
                //sendMessageToServer(userText.getText());
                userText.setText("");
            }

        }
    }
}

Stream.java:

package Stream;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;

public class Stream {
    public boolean isConnected = false;

    Socket socket;

    public Stream(Socket socket) {
        this.socket = socket;
    }

    ObjectInputStream input; ObjectOutputStream output;
    Object data;


    public void connectToServer() throws IOException {
        System.out.println("Connecting..");
        socket = new Socket("thisisatestip.zapto.org", 43594);

        input = new ObjectInputStream(socket.getInputStream());
        output = new ObjectOutputStream(socket.getOutputStream());

        isConnected = true;
        System.out.println(isConnected);
    }

    public void sendData(Object data) throws IOException {
        output.writeObject(data);
        output.flush();
    }

    protected Object recieveData() throws IOException, ClassNotFoundException {
        return data = input.readObject();
    }

    public boolean exists() {
        if(socket.isClosed()) return false; else return true;
    }

}

Answer 1

Always create output output stream before your input stream for Object streams, otherwise you create a deadlock situation.

    output = new ObjectOutputStream(socket.getOutputStream()); 
    // output.flush(); if the underlying stream is buffered
    input = new ObjectInputStream(socket.getInputStream());

The input reads the header written by the output, which won't be there unless the output is created first.