Java Swing文本域问题

Question

I created a GUI using Netbeans which took asked the user to input the content in textfields and textareas . When I'm trying to use it in other classes, the text entered in the textfield does not appear when i use getText method on it. Rather in its place, the text which appears in the textfield specified using the edit text option in Netbeans, appears whenever getText method is used. Is the problem related to some sort of sequencing or order? Because I believe the text from the GUI, is being referenced before the user is actually entering it.

public class GUI extends javax.swing.JFrame {

public GUI() {

    initComponents();
}
public void Grow(){
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jTextField1 = new javax.swing.JTextField();
    jPanel1 = new javax.swing.JPanel();
    username = new javax.swing.JTextField();
    UsernameLabel = new javax.swing.JLabel();
    PasswordLabel = new javax.swing.JLabel();
    subject = new javax.swing.JTextField();
    SubjectLabel = new javax.swing.JLabel();
    jScrollPane1 = new javax.swing.JScrollPane();
    message = new javax.swing.JTextArea();
    jLabel1 = new javax.swing.JLabel();
    salutation = new javax.swing.JTextField();
    jLabel2 = new javax.swing.JLabel();
    sendbutton = new javax.swing.JButton();
    password = new javax.swing.JPasswordField();

    jTextField1.setText("jTextField1");

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jPanel1.setBackground(new java.awt.Color(204, 204, 255));
    jPanel1.setBorder(new        javax.swing.border.LineBorder(java.awt.SystemColor.controlDkShadow, 3, true));

    username.setText("Enter your text here");

    UsernameLabel.setFont(new java.awt.Font("Arial", 1, 13)); // NOI18N
    UsernameLabel.setForeground(new java.awt.Color(255, 51, 51));
    UsernameLabel.setText("Username");

    PasswordLabel.setFont(new java.awt.Font("Arial", 1, 13)); // NOI18N
    PasswordLabel.setForeground(new java.awt.Color(255, 51, 51));
    PasswordLabel.setText("Password");

    subject.setText("Enter your text here");
    subject.setCursor(new java.awt.Cursor(java.awt.Cursor.TEXT_CURSOR));
    subject.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            subjectActionPerformed(evt);
        }
    });

    SubjectLabel.setFont(new java.awt.Font("Arial", 1, 13)); // NOI18N
    SubjectLabel.setForeground(new java.awt.Color(255, 51, 51));
    SubjectLabel.setText("Subject");

    message.setColumns(20);
    message.setRows(5);
    message.setText("Enter your text here");
    jScrollPane1.setViewportView(message);

    jLabel1.setFont(new java.awt.Font("Arial", 1, 13)); // NOI18N
    jLabel1.setForeground(new java.awt.Color(255, 51, 51));
    jLabel1.setText("Message");

    salutation.setText("Enter your text here");

    jLabel2.setFont(new java.awt.Font("Arial", 1, 13)); // NOI18N
    jLabel2.setForeground(new java.awt.Color(255, 51, 51));
    jLabel2.setText("Salutation");

    sendbutton.setForeground(new java.awt.Color(255, 51, 51));
    sendbutton.setText("Send");
    sendbutton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            sendbuttonActionPerformed(evt);
        }
    });

    password.setText("Enter your text here");

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jScrollPane1)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jLabel2)
                        .addComponent(SubjectLabel))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(salutation)
                        .addComponent(subject))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(UsernameLabel, javax.swing.GroupLayout.Alignment.TRAILING)
                        .addComponent(PasswordLabel))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(username)
                        .addComponent(password))
                    .addGap(47, 47, 47))
                .addComponent(jLabel1)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                    .addGap(0, 0, Short.MAX_VALUE)
                    .addComponent(sendbutton)))
            .addContainerGap())
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(username, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(UsernameLabel)
                .addComponent(subject, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(SubjectLabel))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(PasswordLabel)
                .addComponent(salutation, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel2)
                .addComponent(password, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 20, Short.MAX_VALUE)
            .addComponent(jLabel1)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 185, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(11, 11, 11)
            .addComponent(sendbutton))
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        


private void subjectActionPerformed(java.awt.event.ActionEvent evt) {                                        
    // TODO add your handling code here:
}                                       

private void sendbuttonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    // TODO add your handling code here:
    MMMMain object = new MMMMain();
    object.MassMail();

}                                          

/**
 * @param args the command line arguments
 */
public void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new GUI().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JLabel PasswordLabel;
private javax.swing.JLabel SubjectLabel;
private javax.swing.JLabel UsernameLabel;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextField jTextField1;
public javax.swing.JTextArea message;
public javax.swing.JPasswordField password;
public javax.swing.JTextField salutation;
public javax.swing.JButton sendbutton;
public javax.swing.JTextField subject;
public javax.swing.JTextField username;
// End of variables declaration                   
}

Answer 1

Is the problem related to some sort of sequencing or order? Because I believe the text from the GUI, is being referenced before the user is actually entering it.

Regardless your code doesn't actually recreate your problem, Swing works in an event-driven scenario. This means an event must happen if you want to get the text field's text properly. For instance:

JTextField textField = new JTextField(20);
JFrame frame = new JFrame("Sample");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(textField);
frame.pack();
frame.setVisible(true);

System.out.println(textField.getText());

Then nothing will be printed because the getText() call happens before the user has had even the chance to write anything. But if you do this:

final JTextField textField = new JTextField(20);
textField.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent evt) {
        System.out.println(textField.getText());
    }
};

JFrame frame = new JFrame("Sample");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(textField);
frame.pack();
frame.setVisible(true);

Then the text will be printed when user types some text and press Enter key in the text field. This is because an ActionEvent is fired and text field has attached an ActionListener which listens to those events and does something in response. You can read more about it in Writing Event Listeners section of the Swing tutorial .