使用来自另一个类的JFrame

问题描述

我试图将一些文本附加到同一个包中的另一个类的 JTextArea 中，这是一个小问题。以下是与JFrame相关的主要类：

Hi I'm small a little issue trying to append some text to a JTextArea from another class within the same package. Below is the main class that pertains to the JFrame:

  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地重新创建问题，但每当运行追加功能时，jFrame的文本区域中都不会显示任何内容。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。

I included test variables just to easily recreate the issue but whenever the append function is run nothing appears in the text area of the jFrame. In my scenario I'm having the client receive text from a server then append it to the text box.

BTW我正在为JFrame使用IntelliJ GUI设计器。我只包含了重新创建问题所需的代码。我还在尝试创建MCVE问题，所以请随时告诉我我所犯的错误。

BTW I'm using the IntelliJ GUI designer for the JFrame. I've only included code needed to recreate the problem. I'm still trying to create MCVE questions so feel free to let me know mistakes I made.

推荐答案

你应该传递客户端通过构造函数进入 ServerThread 。您在 run（）中实例化的客户与客户端您在 main（）中创建的。所以你的 ServerThread 类就像

You should pass Client into ServerThread via the constructor. The Client you are instantiating within run() is not the same reference to the Client you created in main(). So your ServerThread class would be something like

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)
    {}
}

你的 startClient（）方法会更新为这样的东西

Your startClient() method would be updated to something like this

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();
    }
}





---

所有这一切，

---

All that being said,

我建议从客户端移出 main（） 并进入一个与Swing UI代码不相关的类。这样的事情：

I would recommend moving your main() out of Client and into a class that isn't so coupled to the Swing UI code. Something like this:

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
    }
}

您的客户端的构建更像是一个实例对象

Your Client is then built more like an instance object

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
    }
}

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