java - 使用另一个类中的 JFrame

Question

嗨，我在尝试将同一包中另一个类的一些文本附加到 JTextArea 时遇到了一个小问题。下面是与 JFrame 相关的主类:

  public class Client extends JFrame{

        //Static variables
        private static final String host = "localhost";
        private static final int portNumber = 4444;

        //Variables
        private String userName;

        //JFrame Variables
        private JPanel contentPanel;
        private JTabbedPane panel_Social;
        private JPanel jpanel_Social;
        private JPanel jpanel_Chat;
        private JTextArea textArea_Receive;
        private JTextField textField_Send;
        private JTextArea textArea_ClientList;
        private JButton btn_Enter;


        public JTextArea getTextArea_Receive(){
            return this.textArea_Receive;
        }

        //Constructor
        private Client(String userName, String host, int portNumber){
            this.userName = userName;
            this.serverHost = host;
            this.serverPort = portNumber;
        }

        public void main(String args[]){
            //Requests user to enter name
            String readName = null;
            Scanner scan = new Scanner(System.in);
            System.out.println("Please enter username");
            readName = scan.nextLine();

            //Start client
            Client client = new Client(readName, host, portNumber);
            client.startClient(scan);
        }

        private void startClient(Scanner scan){
            try{
                //Create new socket and wait for network communication
                Socket socket = new Socket(serverHost, serverPort);
                Thread.sleep(1000);

                //Create thread and start it
                serverThread = new ServerThread(socket, userName);
                Thread serverAccessThread = new Thread(serverThread);
                serverAccessThread.start();
            }
        }
    }


Below is the serverThread class

    public class ServerThread implements Runnable{

        private Socket socket;
        private String userName;
        private boolean isAlived;
        private final LinkedList<String> messagesToSend;
        private boolean hasMessages = false;

        //Constructor
        ServerThread(Socket socket,  String userName){
            this.socket = socket;
            this.userName = userName;
            messagesToSend = new LinkedList<String>();
        }

        public void run(){   
            try{
                Client test1 = new Client();
                JTextArea test2 = test1.getTextArea_Receive();
                String test3 = "Hello World";
                test2.append(test3);
            } catch (IOException e){
}
    }

我包含测试变量只是为了轻松重现问题，但每当运行追加函数时，jFrame 的文本区域中不会出现任何内容。在我的场景中，我让客户端从服务器接收文本，然后将其附加到文本框。

顺便说一句，我正在为 JFrame 使用 IntelliJ GUI 设计器。我只包含了重现问题所需的代码。我仍在尝试创建 MCVE 问题，因此请随时让我知道我犯的错误。

Answer 1

您应该通过构造函数将 Client 传递到 ServerThread 中。您在 run() 中实例化的 Client 与您在 main() 中创建的 Client 的引用不同>。所以你的 ServerThread 类会是这样的

ServerThread(Client client, Socket socket,  String userName) {
    this.client = client;
    this.socket = socket;
    this.userName = userName;
    messagesToSend = new LinkedList<String>();
}

public void run() {
    try
    {
        JTextArea test2 = this.client.getTextArea_Receive();
        String test3 = "Hello World";
        test2.append(test3);
    } 
    catch (IOException e)
    {}
}

您的 startClient() 方法将更新为类似这样的

private void startClient(Client client, Scanner scan)
{
    try
    {
        //Create new socket and wait for network communication
        Socket socket = new Socket(serverHost, serverPort);
        Thread.sleep(1000);

        //Create thread and start it
        ServerThread serverThread = new ServerThread(client, socket, userName);
        serverAccessThread.run();
    }
}

<小时/>

话虽这么说，

我建议将 main() 从 Client 移出，并移至与 Swing UI 代码耦合程度较低的类中。像这样的事情:

public class MySwingApplication {

    private static final String host = "localhost";
    private static final int portNumber = 4444;

    public static void main(String[] args) {
        // Requests user to enter name
        // Start client
    }
}

然后，您的Client将更像实例对象一样构建

public class Client extends JFrame {
    public JTextArea getTextArea_Receive(){
        // Return the text area
    }

    // Constructor -- public to allow instantiation from main()
    public Client(String userName, String host, int portNumber) {
        // Do stuff
    }

    private void startClient(Scanner scan) {
        // Show the JFrame on screen
        // Spawn Server
    }
}