java - 为什么我的文本区域不显示

Question

我正在尝试实现一个程序，其中客户端将向服务器端发送修复消息，并且服务器端的 UI 将在文本区域上显示修复消息。但是，当我启动程序时，文本字段和所有标签都会显示，但文本区域除外。当我尝试从客户端发送消息时，除了文本区域之外，一切都正常。

代码

    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.io.PrintWriter;
    import java.net.ServerSocket;
    import java.net.Socket;
    import java.util.Scanner;
    import java.util.StringTokenizer;
    import java.awt.*;        // using AWT containers and components
    import java.awt.event.*;  // using AWT events and listener interfaces

    import javax.swing.JScrollPane;
    import javax.swing.JTextArea;

    public class TcpServerCompareCSV extends Frame implements ActionListener , WindowListener  {        

           private Label lblPort;       // declare component Label
           private TextField tfPort;    // declare component TextField     
           private int port;            // port number

           private Label lblLocation;       // declare component Label
           private TextField tfLocation;    // declare component TextField    
           private String fileLocation;     // csv file location

           private Button btnCount;   // declare component Button            //________________________________________________________________________________\\

           private Label lblCSVLine;        // declare component Label from csv file line, server side
           private TextField tfCSVLine;     // declare component TextField  from csv file line, server side    
           private String CSVLine;          // port number

           private Label lblFIXMsg;     // declare component Label from csv file line, server side
           private JTextArea tfFIXMsg;  // declare component TextField  from csv file line, server side    
           private String FIXMsg;           // port number
           private JScrollPane jScrollPane1;//________________________________________________________________________________\\
           /** WindowEvent handlers */
           // Called back upon clicking close-window button
           @Override
           public void windowClosing(WindowEvent e) {
              System.exit(0);  // terminate the program
           }

           //constructor for frame
           public TcpServerCompareCSV () {
              setLayout(new FlowLayout());
                 // "this" Frame sets its layout to FlowLayout, which arranges the components
                 //  from left-to-right, and flow to next row from top-to-bottom.

              lblPort = new Label("Port");          // construct Label
              add(lblPort);                         // "this" Frame adds Label

              tfPort = new TextField("0", 40);  // construct TextField
              tfPort.setEditable(true);         //edit text
              add(tfPort);                      // "this" Frame adds tfCount
           //   tfPort.addActionListener(this);     // for event-handling

              lblLocation = new Label("CSV File Location"); // construct Label
              add(lblLocation);                             // "this" Frame adds Label

              tfLocation = new TextField("text", 40);       // construct TextField
              tfLocation.setEditable(true);                 //edit text
              add(tfLocation);                              // "this" Frame adds tfCount
          //________________________________________________________________________________\\

              setTitle("compare");      // "this" Frame sets title
              setSize(800,200);        // "this" Frame sets initial window size
              setVisible(true);         // "this" Frame shows

              lblCSVLine = new Label("CSV Line");           // construct Label
              add(lblCSVLine);                              // "this" Frame adds Label

              tfCSVLine = new TextField("text", 40);        // construct TextField
              tfCSVLine.setEditable(false);                 //edit text
              add(tfCSVLine);                               // "this" Frame adds tfCount

              lblFIXMsg = new Label("FIX message from client");             // construct Label
              add(lblFIXMsg);                               // "this" Frame adds Label

              tfFIXMsg = new JTextArea();       // construct TextField
              tfFIXMsg.setColumns(20);
              tfFIXMsg.setLineWrap(true);
              tfFIXMsg.setRows(50);
              tfFIXMsg.setWrapStyleWord(true);
              tfFIXMsg.setEditable(false);                  //edit text
              add(tfFIXMsg);                                // "this" Frame adds tfCount

              jScrollPane1 = new JScrollPane(tfFIXMsg);         

  add(jScrollPane1);

              btnCount = new Button("Enter"); // construct Button
              add(btnCount);                  // "this" Frame adds Button
              btnCount.addActionListener(this); // for event-handling        
              addWindowListener(this);
                // "this" Frame fires WindowEvent its registered WindowEvent listener
                // "this" Frame adds "this" object as a WindowEvent listener

           }

           /** ActionEvent handler - Called back when user clicks the button. */
           @Override
           public void actionPerformed(ActionEvent evt) {
            // Get the String entered into the TextField tfPort, convert to int
              port = Integer.parseInt(tfPort.getText());
              fileLocation = tfLocation.getText();
              String csvName = fileLocation;                  
            /*
            Scanner console = new Scanner(System.in);
            System.out.println("Type in CSV file location: ");
                //String csvName = console.nextLine();
                String csvName = "C:\\Users\\I593458\\Downloads\\orders.csv";

    */    
          ServerSocket serverSocket = null; 

          try { 
               serverSocket = new ServerSocket(port); 
              } 
          catch (IOException e) 
              { 
               System.err.println("Could not listen on port: 57635."); 
               System.exit(1); 
              }         
          Socket clientSocket = null; 
          System.out.println ("Waiting for connection.....");        
          try { 
               clientSocket = serverSocket.accept(); 
              } 
          catch (IOException e) 
              { 
               System.err.println("Accept failed."); 
               System.exit(1); 
              }         
          System.out.println ("Connection successful");
          System.out.println ("Waiting for input.....");

          PrintWriter out = null;
        try {
            out = new PrintWriter(clientSocket.getOutputStream(), 
                                                true);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
          BufferedReader in = null;
        try {
            in = new BufferedReader( 
                      new InputStreamReader( clientSocket.getInputStream()));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

          String inputLine, outputLine;        
          try {
            while ((inputLine = in.readLine()) != null) 
                  { 
                   System.out.println ("Server: " + inputLine); 
                   tfFIXMsg.setText(inputLine);
                   if (inputLine.trim().equals("Bye.")) {
                       System.out.println("Exit program"); 
                       break;
                       }                       
                   Scanner input1 = new Scanner(new File(csvName));
                   Scanner input2 = new Scanner(new File(csvName));
                   Scanner input3 = new Scanner(new File(csvName));
                   Scanner input4 = new Scanner(new File(csvName));                    

                   String csvline = getCsvLineVal (getLocation34CSV(getTag34Value(Tag34Location(getTagCSV( parseFixMsg(inputLine ,inputLine))), getValueCSV( parseFixMsg(inputLine ,inputLine))), getVal34(input1,  input2)), getCSVLine( input3,  input4) );
                   outputLine = compareClientFixCSV( getTagCSV( parseFixMsg(inputLine ,inputLine)), getValueCSV(parseFixMsg(inputLine ,inputLine)), getCSVTag(csvline), getCSVValue(csvline));                    
                   out.println(outputLine);
                   tfCSVLine.setText(outputLine);
                   input1.close();
                   input2.close();
                   input3.close();
                   input4.close();                    
                  }
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }              

          out.close(); 
          try {
            in.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
          try {
            clientSocket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
          try {
            serverSocket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
  }

Answer 1

将 textArea 添加到 JScrollPane，然后不对 Pane 执行任何操作。

jScrollPane1 = new JScrollPane(tfFIXMsg);

您需要add(jScrollPane1);