JScrollPane ne fonctionne pas avec JPanel

Question

J'essaie d'ajouter la barre de défilement avec le JTextArea mais cela ne fonctionne pas et le contenu sort du textArea. J'ai suivi les quelques articles mais je n'ai trouvé aucun exemple avec le JPanel tous les exemples sont disponibles avec le JFrame. Actuellement, nous sommes limités à utiliser le JFrame donc nous devons le faire sans l'utiliser. S'il vous plaît trouver le code ci-dessous c'est comment je suis en train d'implémenter le parchemin avec teatArea et s'il vous plaît me guider ce que je fais mal. L'aide sera appréciée.

GUI of below code

code

public class CreatePanel extends JPanel 
{ 
    private Vector athleteList; 
    private CountPanel cPanel; 

    private JTextField txt_firstName; 
    private JTextField txt_lastName; 
    private JTextField txt_sport; 

    private JButton btnNewButton; 

    private JLabel lbl_error; 
    private JLabel lblNewLabel; 
    private JLabel lblNewLabel_1; 
    private JLabel lblNewLabel_2; 
    private JList list; 
    private JTextArea textArea; 
//Constructor initializes components and organize them using certain layouts 
public CreatePanel(Vector athleteList, CountPanel cPanel) 
    { 
    this.athleteList = athleteList; 
    this.cPanel = cPanel; 
    ButtonListener buttonListener = new ButtonListener(); 
    //organize components here 

    txt_firstName = new JTextField(); 
    txt_firstName.setColumns(10); 

    txt_lastName = new JTextField(); 
    txt_lastName.setColumns(10); 

    txt_sport = new JTextField(); 
    txt_sport.setColumns(10); 

    lblNewLabel = new JLabel("First Name"); 
    lblNewLabel_1 = new JLabel("Last Name"); 
    lblNewLabel_2 = new JLabel("Sport"); 

    lbl_error = new JLabel("error"); 
    lbl_error.setForeground(Color.RED); 
    lbl_error.setVisible(false); 

    list = new JList<Athlete>(); 

    btnNewButton = new JButton("Create an Athlete"); 
    btnNewButton.addActionListener(new ButtonListener()); 


    textArea = new JTextArea(16,58); 
    JScrollPane scroll = new JScrollPane (textArea); 
    scroll.setVerticalScrollBarPolicy (ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); 
    textArea.setEditable(false); 

    add(scroll); 
    GroupLayout groupLayout = new GroupLayout(this); 
    groupLayout.setHorizontalGroup(
     groupLayout.createParallelGroup(Alignment.LEADING) 
      .addGroup(groupLayout.createSequentialGroup() 
       .addGroup(groupLayout.createParallelGroup(Alignment.LEADING) 
        .addGroup(groupLayout.createParallelGroup(Alignment.LEADING) 
         .addGroup(groupLayout.createSequentialGroup() 
          .addContainerGap() 
          .addGroup(groupLayout.createParallelGroup(Alignment.LEADING) 
           .addComponent(lblNewLabel) 
           .addComponent(lblNewLabel_1) 
           .addComponent(lblNewLabel_2)) 
          .addGap(53) 
          .addGroup(groupLayout.createParallelGroup(Alignment.LEADING) 
           .addComponent(txt_firstName, GroupLayout.DEFAULT_SIZE, 87, Short.MAX_VALUE) 
           .addComponent(txt_lastName, GroupLayout.DEFAULT_SIZE, 87, Short.MAX_VALUE) 
           .addComponent(txt_sport, GroupLayout.DEFAULT_SIZE, 87, Short.MAX_VALUE))) 
         .addGroup(groupLayout.createSequentialGroup() 
          .addGap(59) 
          .addComponent(btnNewButton))) 
        .addGroup(groupLayout.createSequentialGroup() 
         .addContainerGap() 
         .addComponent(lbl_error))) 
       .addGap(5) 
       .addComponent(textArea, GroupLayout.DEFAULT_SIZE, 234, Short.MAX_VALUE) 
       .addContainerGap()) 
    ); 
    groupLayout.setVerticalGroup(
     groupLayout.createParallelGroup(Alignment.LEADING) 
      .addGroup(groupLayout.createSequentialGroup() 
       .addGroup(groupLayout.createParallelGroup(Alignment.LEADING) 
        .addGroup(groupLayout.createSequentialGroup() 
         .addGap(47) 
         .addComponent(lbl_error) 
         .addGap(53) 
         .addGroup(groupLayout.createParallelGroup(Alignment.BASELINE) 
          .addComponent(txt_firstName, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE) 
          .addComponent(lblNewLabel)) 
         .addPreferredGap(ComponentPlacement.UNRELATED) 
         .addGroup(groupLayout.createParallelGroup(Alignment.TRAILING) 
          .addComponent(lblNewLabel_1) 
          .addComponent(txt_lastName, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)) 
         .addPreferredGap(ComponentPlacement.UNRELATED) 
         .addGroup(groupLayout.createParallelGroup(Alignment.BASELINE) 
          .addComponent(txt_sport, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE) 
          .addComponent(lblNewLabel_2)) 
         .addPreferredGap(ComponentPlacement.UNRELATED) 
         .addComponent(btnNewButton)) 
        .addGroup(groupLayout.createSequentialGroup() 
         .addContainerGap() 
         .addComponent(textArea, GroupLayout.DEFAULT_SIZE, 278, Short.MAX_VALUE))) 
       .addContainerGap()) 
    ); 
    setLayout(groupLayout); 
    } 


    //ButtonListener is a listener class that listens to 
    //see if the button "Create an Athlete" is pushed. 
    //When the event occurs, it adds an athlete using the information 
    //entered by a user. 
    //It also performs error checking. 
    private class ButtonListener implements ActionListener 
    { 
    public void actionPerformed(ActionEvent event) 
    { 

     //TO BE COMPLETED 
     if(txt_firstName.getText().length() == 0 || txt_lastName.getText().length() == 0 || txt_sport.getText().length() == 0) 
     { 
      lbl_error.setText("Please enter all fields."); 
      lbl_error.setVisible(true); 
     } 
     else 
     { 
      Athlete athlete = new Athlete(); 
      athlete.setFirstName(txt_firstName.getText()); 
      athlete.setLastName(txt_lastName.getText()); 
      athlete.setSport(txt_sport.getText()); 
      athleteList.add(athlete); 
      textArea.setText(textArea.getText().concat(athlete.toString())); 
      lbl_error.setText("athlete added."); 
      //clearControls(); 
     } 
    } //end of actionPerformed method 
    } //end of ButtonListener class 

    private void clearControls() 
    { 
    txt_firstName.setText(""); 
    txt_lastName.setText(""); 
    txt_sport.setText(""); 
    } 
} //end of CreatePanel class 

Answer 1

Votre GroupLayout ne pas ajouter la scroll à la mise en page, mais le textArea:

.addComponent(textArea, GroupLayout.DEFAULT_SIZE, 234, Short.MAX_VALUE) 

Essayez d'ajouter le scroll comme

.addComponent(scroll, GroupLayout.DEFAULT_SIZE, 234, Short.MAX_VALUE)